How is her night sleep? It seems to me like you might be heading into the 3-2 transition, where she would move to a higher A time and 2 naps of 1.5 - 2 hours + a catnap. Looking at your routine, what stood out to me was that you are getting a good morning nap but it is still only 45-50 minutes. This could mean that she is having trouble transitioning between sleep cycles - is her room dark? Could there be any noise disturbing her? You could try wake to sleep to try to help her transition through this and lengthen the nap.
How do I address habitual wakings? (wake-to-sleep and other methods)Then, looking at the later naps, it does seem like a case of under tiredness to me because of the extremely short A time. I know you said that she gets super cranky and wants to sleep but you might
have to keep her up in order to lengthen the nap. I found that with mine, she would sometimes
seem really tired and would sleep easily but would not be tired enough to do a long nap, so she would be up and refreshed in 30-40 minutes. I had to keep her up any which way, and stick to a more appropriate A time. I pretty much stopped going by sleepy signs around 4 months and kept an eye on the clock instead. It did take E a few days to adjust to A time changes but when she did, naps lengthened and it really helped.
The great thing about the 3-2 transition is that things honestly do get a lot better from here on out. Simply dropping a nap is a big relief. With mine though, I was never able to get 2 long naps + the catnap, and so we got one long morning nap of 1.5 hours + 2 catnaps of 30-45 minutes. I'm posting a link with more information regarding this transition.
All about the 3-2 transition- 5/6 monthsAverage A times- BOOKMARK ME! Hope this helps:) Good luck
PS: Have you visited our Birth Clubs yet? You can meet a ton of mums going through similar experiences. The support is amazing! This is the one you would post in
0-6 months, Part 1