10 Month Old Female Great Dane

Question
I have a few haha!

I very recently(a week ago) adopted a 10 month old great dane, female. As a
brand new dog owner i have a million concerns and questions. She is well
trained - sit, stay, law down (most times), and does a few tricks for treats.
She walks extremely well while on her leash. The first two days she was with
us she was a perfect angel - very calm, mostly layed in her bed unless to
come over to be pet for a bit. however the latest few days she has become
more rambunctious, a bit whiny - it mostly seems like she wants attention,
but im just not positive. She is taken outside several times a day - when she
wakes up, after breakfast, once or twice in the afternoon, she goes to the dog
park and runs around for about an hour, and then she goes out in the evening
Three of my main concerns are :

She has not been spayed. I absolutely intend on spaying her. Could her recent
rambunctious behaviour (she also seemed more aggressive at the dog park
today which she has never been with us thus far and we were told she never
is ) be on account of her possibly going into heat? I was told she has not gone
into heat yet. I would spay her immediately however i dont happen to have
that kind of money on hand immediately. Any thoughts or advice? I may just
be over reacting about her behavior lol... to be honest i just dont know what
to expect and what is normal...etc

She has not been eating nearly as much as I had expected. She will not eat
her dry kibble(she is on the same thing her previous owners had been
feeding her) unless i mix it with something or put a sauce on it. Today i have
had her bowl full of plain kibble and she has probably only taken a few bites
all day long. I am more than willing to switch her to something better. Any
suggestions? How much should she be eating per day( 10 months old and
about 110 lbs)? Do you suggest feeding real food, or real food mixed with
kibble? I have added ground beef and veggies to her kibble and she seems to
like it, also some fish, chicken...etc. I want her to be as healthy as possible
and have had trouble finding exactly which nutritional needs she has - i get
conflicting answers.

Her previous owners lived in a house with a large backyard. I live in a
smallish apartment in a downtown area. The closest park by me i cannot have
her off leash, and the dog park is too far to be taking her every time she
needs to go out. She will go pee on the leash, but thus far has not gone poo.
She has only gone poop while off the leash at the dog park. Any suggestions?  
This only concerns me as because we only go to the dog park once a day, she
has only been pooping once. I can tell if this is on account of her not eating a
ton, or if she just refuses to go on the leash. She has pooped in the house
twice as a result during the night time even after being taken outside before
bed ( only goes pee not poo) She also seems to not be on any type of
schedule, when she starts whining to go out, she needs to go NOW. I am
assuming this is because it was easy for the previous owner to just open the
park door and let her into the backyard. i unfortunately cannot do this and
need to have her going at certain times, or at least something a bit more
reasonable.

Also, what are the best ways to teach a dog to 'come'? I would feel
comfortable letting her off leash - however the second i take it off she thinks
its play time and takes off. If i felt that i trusted her enough to come when i
called her then i would be okay however she does not come, she simply
thinks were playing a game.

Sooo sorry if i am not making sense or rambling. Like i said i am just
concerned and want to nip any issues in the butt as soon as i can. I do intend
to also get some professional training, just to get us all on the same boat.

Any info or advice is GREATLY appreciated! Thank you.  

Answer
Congratulations on your recent adoption! I know that you have many questions that you want answered. I will try to help you as much as I can!

Females can get more aggressive when they begin going into heat. I am not sure where you are located but I would suggest that you contact a local SPCA or Humane Society in your area. This is also a great link:
http://www.spayusa.org/
This is a voucher program for people who want to spay/neuter their dogs but do not have the money. These are low cost programs and are not available in every state. I would suggest that you do some research on low cost spay/neuter programs.

What brand food is she currently eating? Remember that she has been in your home for just over a week so she may not be fully in her comfort zone. Although table food will not harm her, it will make her a picky eater. From my experience, I have always just fed a high quality diet and not added things to food. The whole reason that dog food is formulated is so that owner's don't have to make or add anything into their dogs meals.

A 10 month old puppy should be eating anywhere from 6-10 cups a day, depending on the brand of food.

As far as her using the bathroom is concerned, from what you are describing, I think you are correct that she was not on a schedule. Has she been consistently going to the bathroom on the house on a nightly basis? This is just going to take consistency, if that means that you need to set your alarm clock to take her out in the middle of the night then that is something you will need to do. I do believe that you will need to spend a little bit more time outside with her so that she has a chance to go potty. Also, being that she is going in the house, the food maybe the issue. If she is not eating much and is still going to the bathroom 3 times during the day, you are going to need to put her onto a different food.

As far as teaching her to come. She has not had enough time to adjust to you as a family. You have only had her just over a week. Allow her time to build a bond with you. Nothing is going to happen overnight. I would suggest that even though she does know her basic commands, in 3 weeks you sign up somewhere for a refresher course. Obedience gives dogs confidence and also builds a bond between dog and owner. If you look for immediate results, you are going to set her up for failure and you will become frustrated. For the time being, to keep her close to you but give her enough space to exercise I would suggest that you get a big dog flexi-leash or a long line training leash. This will give her space to run around, but still keeps her attached to you. Then practice the come ON-LEASH whenever you can. You cannot start off leash and expect the dog to come to you, you have to practice having her come on leash and get a great reward.

I hope this answers your questions please let me know if you have any other concerns that you need answers for.