Sounds like UT wakings to me, some of his A times on those days really are quite short for a 10.5 month old and may be why you are getting short naps too.
Essentially once you get to 4h A you need to choose which nap to keep long, and which to cut short/'cap'. With a long morning nap the day can look like:
WU 6
Nap 10-11.30/12 (allow to sleep)
Nap 3/3.30/4 for 30-45 mins
BT 7 (as you can see the day gets longer but a 13h day is plenty - if you want to keep an earlier BT you'd need to cut the pm nap even shorter but the aim is to hold off the 2-1 for a while so letting the day go longer is often a better short-term option)
With a short am nap you'd go for something like:
WU 6
Nap 9.30 for 30-45 mins
Nap 1/1.30 for 1.5-2h
BT 7ish
(shorter A times earlier in the day due to the shorter nap, then a longer stretch awake before bed)
What do you think?