I have a short napper too. He is 4.5mo and has been a 30 min napper since he got out of the sleepy newborn phase. Here a few things I tried, that sadly didn't work for me but maybe can work for you
1. Logged A times like a hawk. I tried to work on each nap separately, so for the morning nap one day I would try 1 hour 15, that didn't work so then I would shorten it by 10 min the next day and see if that got me a good morning nap. If it didn't I would lengthen it 10 min the next, etch
2. Try to figure out if it was hunger
3. Tried make sure he was comfy. Is the room dark enough, cool enough, hot enough?
There are others, but those were the biggies that I can think of!
If he wakes early , I do something AP to extend his nap. Usually rock him and move him to this vibrating bassinet thing that we have. If he isn't asleep in about 30 more min, I just get him up and adjust my day accordingly. Its tough, but you'll figure out what works for you!