It is a real struggle and I keep telling myself that I'm just trying to teach her to fall asleep (like riding a bike) but somehow when I'm in the thick of it, I want to lose my mind and scream! And I tell her over and over "i know you're frustrated - I'm here for you" but then I get so frustrated. I think I'm going to develop a phobia of babies and sleeptime because sometimes it really makes me anxious when sleeptime comes along! So much for the confidence that Tracy talks about in her book!
I am no expert, but I feel your pain mamma. The first 25-50 min of every nap I am on edge. Hoping, worrying and stressing that my LO is going to wake up.
I can tell you that the first 5-7 days when the short naps started for me I felt like nothing was working. PU PD was so awful and draining and I began to second guess what her mantra cries were. Before the short naps started I felt like I knew her cues. Then all of a sudden I felt like I didn't know my baby at all. It was/is maddening!!
But we did start to see results and we are now getting consistently better naps... Although we just had a 25 minuter today.
At this age ( my LO is just shy of 6months) they are changing so quickly you have to be prepared to up the AT more frequently then you would think.
As to how to proceed after a short nap I read an interview with Tracy in the archives of the forum where she says. If your baby has no routine and you are just starting one stick to the times as best you can, but if you have a routine it is best to try and extend short naps with shush/Pat, PU PD etc. Until time for next feed. Then if baby falls asleep during the feed keep LO up 10 mins post them put back to bed. If they don't fall asleep keep them up 30 mins post feed them back to bed.
That is what we have been doing with decent success.
Good luck!