Feral mama cat acts like had kittens but belly is getting even bigger

[Girltropix]

So, this will have to be a theory question because this cat cannot be trapped (we've been trying for over a year) she has had 2 litters of 4 kittens and what we do know is she gets pregnant 2 weeks after giving birth. I have a plywood home for her to have kittens in with 2 entrances but I failed to make a way to see inside. She is a very protective mother who will attach if you go near her kittens. Her last batch she kept so quiet that we didn't know if she even had live kittens born until she moved them to a potted plant at 6 weeks old! Not a single mew or sound out of her the whole 6 weeks so listening is useless.
Now - timing wise she started being in her house all the time right when expected to give birth. Rushing right back in after eating. All normal new mom behavior except her belly started getting bigger again. A lot bigger. So maybe she didn't have them yet? It's been 3 weeks so she's likely one week pregnant again. Eating normal. Behavior is not as aggressive as before. I did catch a raccoon about to enter her house. Scared him off and secured the patio better. Raccoons are attracted to kittens.
She won't leave long enough for me to reach in to feel for kittens.
Any thoughts? Her nipples don't show nursing activity when she has kittens so can't use that indicator.

 

[Sarthur2]

What happened to her previous litters of kittens?

Have you tried setting a proper trap for her with food in it?

 

[Girltropix]

What happened to her previous litters of kittens?

Have you tried setting a proper trap for her with food in it?

I found homes for her previous kittens. There was one we couldn't trap for too long so when we did catch him it was a TNR.

We have been trying to catch the mom for over a year. 5 different types of traps. She won't go inside even when all other food has been taken away for 3 days. She just slept on top of the trap! She is very very intelligent!
I should mention the people involved with her are a rescue .

 

[StefanZ]

So she does use this maternity home, but you cant see inside?... Have some sort of camera installed? Nowadays there are cheap online cameras... You cant obviously do it NOW, but for next time, if there is any next time... Im no expert on the exact technical solutions, you will find out for yourself once you begin to look into it.

Re her situation.
Seems to have delivered but the belly seems to be bigger and bigger.
ONE interpretation which I hope isnt true, is she is seriously sick. But I hope, IF she is sick, she will come to you and seek help. They often do so WHEN they become seriously ill! Even if verry shy otherwise. IF this happens, AND she survives, the socializing will become easy, if she survives.

But there is another fully possible variation here:

she has two litters simultaneously. She gave life to the first one, and several weeks afterwards, she will deliver next batch, and this too may be entirely healthy with any luck... And I dearly hope this is the case here.

That is not common but not unique either with cats (but unique with human women). Breeders see this seldom or never, because they usually have control over the matings.
But not uncommon with free living moggies. Because they can be mated anytime. Always when in heat, and sometimes otherwise too.
I had a neighbour, whose cat was from such a second litter. I wont tell the background story.