swordtail and 2 guppys pregnant

Question
I have a male and a female swordtail, and recently have thought she could be pregnant, she just started getting bigger and bigger. Shes not huge at the moment, but when you see her front ways, she looks a bit like a balloon loll. Thing is, i can't be 100% sure, because i can't see a gravid spot, and the reason for that is that she is black, (orange on the top# So how do i know if shes pregnant and not just fat #altho she shouldn't be fat, i don't overfeed her#.
Also, my 2 female guppies look like they are fit 2 burst. They're both in a breeding box #one each of their own) and their gravid spots are huge, and dark black, but doesn't seem like they want to have them. I'm worried that they're stressed and that is the reason they aren't having them. They keep jumping out of their breeding box in the night and when i come into the living room have to get them back in which is probably very stressful for them. I don't want them 2 have the fry in the tank as there is nowhere for them 2 hide at the moment, as all my fish are just getting over white spot, so have had 2 bin all my live plants.

Answer
Clare,

Just keep an eye on her. When she is getting ready she will spend a lot of time at the bottom. Its hard to tell since we don't know when she got pregnant. They usually give birth every 30 days. Since the females can hold onto sperm, she can have babies once a month up to six months even if you don't have a any males in the tank. If they won't stay in, you can do a couple of things. 1. you can get a 3 way breeder. They have lids to keep the females in. They also keep the fry away from the female. Second you can heavily plant the tank with some dense plants and let the females have the babies in the main tank. The plants will give the fry places to hide. Just watch everyone closely. Remember that the female can and will eat the fry so make sure you use a lot of leafy and dense plants