Stopping formula

So I was pretty bad on getting my LO to eat “solids” before a year.. so recently I stopped formula and am giving milk and actual food. My problem is that I feel as if my son isn’t eating enough and still only wants formula as his primary food.. for example breakfast he only eats a few bits of pancakes and has 5oz of milk and that’s it then he doesn’t want fruit or vegetables and he will eat yogurt and stuff for snacks but lunch again he will only eat a little bit and then get tired of eating and want formula.. I’m really worried about him not eating enough..

My doctor told me to stop formula all together and get him eating foods and drink milk water and a tiny bit of juice