Hi Jenny-
Sorry you're having such a hard time right now! Based on what you've told me, I'd go to a 3.5 hr routine and stick to that for a week or so and see what happens. I had Tyler on a 3.5 hr routine around that age for awhile and it worked out great...4 hr EASY didn't click well for us until he dropped his 3rd nap, but that's just us. Once you get to 3.5 or 4 hr EASY, whichever you do, stick with it. Consistency day in and day out will help her body adjust and hopefully get those naps to lengthen. She may just be a short napper, though...Tyler was, and our routine most days was more EASAE. I just kept his feeds on schedule, waking him when necessary and ensuring I wasn't feeding to sleep.
As for skipped naps, yes, you'd continue doing PU/PD or pat/shh or whatever it is for the duration of the whole nap, if needed. If the nap gets skipped, you may have to readjust the rest of the day. Keep in mind, now that she's getting older and more aware of the world, she may be needing a bit more wind down before sleeps. Make sure she's getting some quiet activity time before the nap routine starts to help her wind down a bit.
Keep us posted...HTH!