It does sound like your LO is starting to accumulate some OT.
And yes... Learning new skills can affect sleep for sure!!
You have a few options...
You can take a step back, follow those earlier sleep cues and let her catch up on some sleep. As PP said some babies thrive on the clock others are super sensitive and need a bit more adjustments.
It does not mean you will be out of the woods necessarily she could still be learning to connect sleep cycles so you end up with some 40 min naps again, better than 30
You could persevere with your chosen AT but make adjustments to the timings if those naps depending on when your LO wakes and make use of early BT if needed.
As for feeding to sleep... A couple thoughts on this.... Yes it can become a sleep prop for sure (but that can be fixed in future). You have to decide what is more important right now. Some mammas will use a prop like nursing to get baby onto a solid age appropriate routine, then address that prop later. My thought on that, is that your routine is not awful and you are not too far off age avg AT, so maybe only nursing to sleep so LO can catch up on some sleep occasionally, but not making a habit of it may be another option.
I feel like a rambled through those last thoughts... Do they make sense?
It probably does not help, but I don't know anybody who fully escaped short naps and UT/OT loop around this stage (I am sure these unicorns exist somewhere), so don't be too hard on yourself!
The most important thing is that mamma and baby are happy, and mamma doesn't go too crazy!