if lo has an intolerance at this point to the solids (alot of times lo's digestive systems aren't fully developed at this point..) this could be a reason for the wakings. imo i would recommend cutting it out for a few weeks and seeing if that helps, it wouldhn't hurt any as lo's don't NEED solids until much later anyways as bm/formula is the main source of nutrition. if you really are stuck on feeding the solids, maybe try moving the feeding to the am as it would hopefully pass through lo's system by night if that is the trouble.
it does seem that your lo is napping an awful lot. i would limit that catnap and that would ensure he isn't napping so late and make sure that isn't affecting the sleep at all also. maybe limit the other naps a bit - maybe 1.75hrs in the am and 2hrs in the pm just to be sure he isn't waking b/c he isn't tired enough. in order to get the day to flow smoothly you may want to extend A times by 15 min here and there where possible as well.