I went from no kids (full time) to PT (4 days with 1st child) to 3 days (next child). PT is both the best and worst of both worlds. With PT, I always feel like the house is not quite picked up, etc., and at work (I work on cases/long term projects), I feel like I am never quite getting enough done. But, with that said, I love it!!! It gives me time to be a Mom, volunteer, have my kids in scouts, sports, etc. I try to schedule most Dr appts for my off days.
If you have the option, definitely drop to PT 1st, and see how it goes--the pain of less $$$ is not as traumatic as no $$$. If after a year, you are fine with $$$ and you want more time at home, then you can always quit---but once you quit, you can't always go back.
Lastly, childcare at centers is usually almost the same $$ for 3 day as as 5 days (esp. for 2 and under). I put out lots of feelers, esp. at preschools and churches, asking for someone wanting PT childcare job and we found a church nursery worker who was our nanny for 3X a week for 3 years! good luck. Elaine