sounds like a plan. jj has short napped since 3 months old (until this week, amazingly, but i wont go into that) and been pretty happy with it; i would try and extend for a week and tweak his EASY and then leave it for a bit. had too for my sanity! so i totally get it. and i didnt even have a toddler!!!
so you're doing a great job!!! (i've done the newborn but toddler thing as a nanny,that was hard enough!, and already told my husband we're having a big gap between kids!!)
i'm the same when sleep deprived, i was here ranting last week about how i'd barely slept for months etc we all do it! short naps are often developmental and because she's prem she may not be over that phase yet but could change any time. if she's happy when she wakes but you cant or dont want to resettle her, leave in her in bed until the hour 'nap' is finished. this is often a gentle way to let their body clock know they need to sleep longer while giving you extra Y time, or toddler time
also helps you stay on EASY.
in a month or two when she's older and you've started solids things will be totally different and then you'll have the challenge of managing her longer naps with toddlers routine! see if you can get some naps on the weekends to tide you over this phase. i do hope the night waking improves but like i said, jj and lots of other babies go through a phase of doing that around 3 months so hopefully it'll be over soon! lots of love xxx