my dogs behavior has chnged in the past few days

Question
My boyfriend and I have a 9 month old German shepherd and her behavior has changed these past few days. I'm not sure if maybe she is getting ready to go into heat or if it's just the weather. When we take her out she tries a lot harder to pull away and runs back and forth very fast, getting hyper about everything thing in the surrounding area. She also seems to be thirsty all the time, panting like crazy no matter what I do or how often she drinks water. Should we be concerned about this change or could it be her first heat cycle coming on? I have never had a dog before and have no idea what to expect.

Answer
Why haven't you spayed her?  Flaky behavior is one of the first signs of a dog coming into heat.  There is absolutely no good reason for a new dog owner not to have it taken care of by 6 months.  Cal a vet tomorrow.  If she is already starting into heat, chances are the vet will insist on putting it off.  If she isn't coming into season, it could be some other physical problem needing attention form the vet.  

New dog owners like you that fail to spay neuter their dogs are a big part of the reason we slaughter 10,000,000 dogs a year for lack of homes.  Please don't add to this misery.

No, eventually breeding her isn't a good idea.