Done with bottles

So I’m having a major issue with my son. He’s decided he is a big boy and doesn’t need to drink bottles anymore. So he will drink 2-3 ounces from his bottles then refuse them. He will however eat solid food. And he will eat if you mix it with oatmeal. But then he’s getting in way too much oatmeal just to get the formula down. Having oatmeal 4-5 times a day isn’t ideal. The largest bottle he ever drinks is 6 ounces. But now the last 2 days he doesn’t want to take that. I’m not sure if I should withhold the solid food and keep offering the bottle to push the issue or if I should just feed him solid food to replace. Of course another issue I have is he’s always struggled to gain weight and the formula is higher calorie then solid foods so it’s my preference to have him still taking at the 20 ounces I had been struggling to get into him before this!

Edited to add, sippy cups are worse. He only takes a few sips from them and just plays with the cup.