hi
my dd is only two days older than your LO and we're also having some problems with naps now. plus she's teething...
I can't really offer you any help or advice, as we're having some tough moments now too. but i must tell you that it has all began for us with the growth spurt as well. she was eating all the time [BF with one FF a day, in the evening], napping more often than before, waking up more at night. now, she's eating every 3,5~4 hrs but sometimes naps twice in the middle, lol! I've read many posts about those short naps and I guess it's more or less a developmental issue.
have you tried pat/shush, are you swaddling? we're not swaddling anymore, but dd sleeps/naps in a grobag so it feels a bit like a swaddle to her I guess. pat/shush has never really worked for us but it has for so many Moms/LOs that maybe you could try. maybe you could aslo try extending his A time real slow, 10 to 15 minutes a "cycle" [but only one "cycle" a time, check out this post
https://babywhispererforums.com/index.php?topic=63161.0, it's about transitioning from 3 to 4 hrs EASY]
like I've said, can't really help, but big hugs to you
gotta go, dd's crying
Monika