Help!! 4 mo Chronic crap-napper!!

So my LO hit the 4 month sleep "regression" a couple weeks ago and I was losing my freaking mind...after trying virtually everything I could think of, my cousin suggested I try "Sleep Sense" and sleep train. I took away all the sleep props and she is now falling asleep and staying asleep on her own for the most part, but we are still getting crap naps 20-45 mins during the day. Everything I read says she should be awake for 90-120 mins in between naps but she only seems to last about 60-75 max. Will this change on its own or is she just chronically overtired? Should I try stretching wake times? Or bite the bullet and just make a set schedule and keep her up the 2 hours?? I'm scared to make her more tired and get even worse sleep...any suggestions? TIA