You could try giving him a snac before his nap and lunch after. Alot of people do 3 feeds at this age. Eventualluy, his nap will start later in the day and you may still give him a mid morning snack and then lunch before his nap.
DS is on one nap and this is what we do:
7 wake, bottle
8 breakfast
10 snack
12 lunch
1 bottle, nap
4 wake, snack
6 dinner
8 bottle, bed
He probably doesn't need the 1:00 bottle, but he won't take milk from a sippy cup yet and he is not bf anymore, so I am just trying to get enough milk into him.
HTH!
Kim