Never transplant during flower. New soil will have extra N, which will probably cause your flowers to slow down. Plus, your plants are FINE. Every plant in soil gets root bound. It doesn't matter about final container size. Just keep feeding and watering. Put the plants on a drip tray, so when you water and it runs out, the fabric pot sits in a puddle for a little while and the plant will suck it back up. That will help you water less frequent. When I will be gone for a day or two, I over water and leave them in a puddle. The plants soak that water up quick!
Get to harvest, it won't be an issue. Everything the plant needs, you can provide. The soil is just a home for the roots, like coco or perlite or hydro water. Just a physical space, and small spaces are fine.