Pregnant Platy Not Having Babies

What would cause a pregnant platy to not have the babies? She has been pregnant at least 2 months.

 

Can you post a picture of her?

 

This is her

 

I’ve read that they could hold their babies in for up to four months. Are there any fish that could be dangerous to the fry? She may be holding them in to keep them safe. What’s the temp in the tank and the water perimeters? (Edit: I read that a “Gravid Spot” can be seen if they are pregnant.)

 

3 platies, 5 cories, 4 guppies and 6 glofish danios. 20 long. Water was tested yesterday and was 0 ammonia, 0 nitrites and 10-20 nitrates. Temp stays around 76.

 

Does she have a Gravid spot? Nothing sounds like a threat.

 

I believe so she has a black spot near theback of her belly

 

They cannot hold fry for four months, physically not possible. They can hold them 40 days at most. She could have absorbed or aborted the first batch of fry (or they could have all gotten eaten) and is on the second round from her stored sperm (unless you have a male that could have bred to her after she absorbed/aborted).
She is very chesty which points to being overfed quite a bit, while she is gravid (you can see the area where the fry are growing) you have a bunch of fish that would and do eat fry, most livebearers (if the female cannot find a place to hide securely) will follow the birthing female around and eat the fry as they come out before they can start swimming. Danio are fast enough to catch the fry after they start swimming and most platy will hunt them.
The longest I have had a female hold fry was 38 days, she was massive at that point and finally dropped that evening. She had about 23 fry, which half were eaten pretty much that next morning.

 

Ok thanks. She was the only fish for a bit so it's possible I overfeed her. now that we have more fish will she lose weight? Also no males I there right now but if she used stored sperm would she never have looked "unpregnant"? I'm not worried about the fry I didn't want babies anyways I just keep watching her to see the belly go away to know she is ok.