We had a similar problem with DS and in the end what did it was appealing to his independent streak (which is about a mile wide )
We filled up an ordinary bottle with milk and put it on the coffee table. Not sure if your DS is cruising or pulling himself up yet, but if not then maybe just within reach of crawling or sitting? Then we left him to it.
Within minutes he'd crawled to the table, pulled himself up, got the milk, sat down and drank the lot! As a bf baby, he just hated the passive thing of being fed, as it were - but he was quite happy to feed himself.
We also found (and still do) that he will only drink a couple of ounces of milk from a cup, but he'll drink a whole 8oz bottle down in one if it's in a bottle. He still has one when he wakes up, and he's 2.4 now .
As for solids - he was a very slow started on them too, and completely refused purees - if your DS is shutting his mouth up tight when you try and feed him, you could try Baby Led Weaning? Apologies if you're already doing this!
DS much preferred the independence of BLW, and although he still took to solids very slowly, it was without any major traumas. He now eats like a horse, and there are very few things he won't eat.
No idea if this helps, but hope it does!