Adopted by a mama stray ... questions

Hello! In July I was adopted by a stray cat. Long story short, she walked up to me and cried for help. She was emaciated and alone. I fed her for a few days and when she kept coming back, I took her to the vet. Vet scanned for microchip (none) and said she'd recently had a litter. I found the litter under our woodshed. After a few days, safely got mama and kittens into a safe room in our barn. Continued taking mama and kittens to the vet, treated for parasites, ear infection, begun vaccinations for everyone. Feeding mama and now babies on Purina Pro Plan, per vet's recommendations. Mama cat is only about 7 months old. Babies are now about 7 weeks old. Current plan is to keep mama and one of the kittens, while finding homes for the other three babies when they're ready to separate from mama.

I live in a tiny studio (about 200 square feet), but have built a catio outside (access through a window) which gives the cats another 72 square feet of outdoor space (6 x 12 x 6 feet) with shelves to lie on and room to walk about.

I have two litter boxes inside and one outside in the catio. Do you think that's enough? The catio won't be accessible all the time (night time, or when cold/rainy), so they'd only have access to the two indoor litterboxes during that time.

Is it crazy that I'm tempted to keep mama cat and two of the babies? They're all so young. I've just become so attached to all of them while caring for them. It's kind of killing me to be finding them forever homes (awesome as they will be).