One question in case I can't find the good A time to get a long nap: Do you suggest decreasing the next A time
This can go either way to be honest.
If you put in a full A time LO can become OT (having had a short nap then long A time) which can make her grumpy or cause a shorter next nap (eg OT nap of 20 mins although often easier to resettle and get back to sleep) but it can also help to maintained or establish the routine and could even encourage better napping again.
If you reduce the A time after a short nap you will avoid OT and LO may be happier, but this can also lead to another short (UT) nap and then the cycle continues of short nap, short A.
It's actually personal preference what you choose to do. There are examples in the book of Tracy trying to resettle a nap right up to (or close to) the end of nap time (45 min nap 45 min resettle but LO doesn't sleep) she then gets them up and follows it with a full or almost full A time. This means it is particularly long but LO is more likely to sleep train and get back on track. it's pretty hard work though! Many people prefer to go with the flow a bit more, go a bit gentler and count the A from the end of the short nap, do a full A or just slightly reduced.
As a suggestion you could go for a 1hr 15 A time after a short nap, counting from when she woke rather than when the nap should have ended.
Amazing she slept through the night - I bet you enjoyed that
Lots of growth spurts etc to come though so don't get too comfortable