Ok- I think that you might need to push that A time again as:
1) you are having trouble getting her down for naps
2) she is only sleeping for an hour and
3) the early morning happy wakings- or 'cot parties' as i like to call them
At 4 months you usually look at a 2 hour A time- that;s how you get your 4 hour easy- the theory is 2 hours up, and 2 hours sleep- 4 hours. Even if she only sleeps for 1.5 hours that's still a 3.5 hour easy- which is fine.
The fact that she's having nice big feeds tells me that she needs it- and yesterday she still only had 5 feeds- which is not too bad as she's now STTN (Do a big happy dance for that one!!). Often EBF babies find the move to 4 hour easy hard as they take longer to stretch the full 4 hours.
SOOO- My suggestion- push up the A times again by about 10-15 minutes. Are you familiar with this process? It seemed you've done it before... Your aim is to get close to 4 hours, but don't get greedy and do it all at once (I did this once.. bad... ). If she does a 30 or 35 minute nap then DON"T PANIC- you've pushed her too far and she needs less A time. Just adjust it for the next day and you;ll be fine.
It can be hard to work out the A times when they are up in the morning, my guy often did/does that-n I know thatif he REALLY needs me he'll cry and i;ll wake up.. so i don't panic. You just need to see what works. I found with my guy i had to just ignore worrying about how long he as up before i knew and go for the A time i felt he needed. But all babies are different!
Also- if she wakes up from the nap at 40-45 mins happy then in that case with my guy i could never get him to resettle. Try for sure- but if after a fe days it doesn't work- cut your losses, get her up and start a new A time- it makes a short nap much less stressful when you know you don't have a screaming match at the end!
Make sense? Please let me know if you need more info!