I dropped to 3 bottles at 9 months (just before, I think actually), and I did increase the amount then too. I find that he doesn't always want the full bottle, then at other times he drains it.
If he wants more solids then go with it and let him have it, the only thing to really keep an eye on is that its not impacting on his milk intake. My LO had been having the same meals as the rest of the family for a while by the time he was 9 months. Just ensure that the foods are suitable etc. So my LO loves pasta, bolognaise, cottage pie, eggs, lasagne, fish, bread, etc.
He may not always want three full meals - for example, I find that my LO tends to have a decent breakfast and dinner, but lunch tend to be more of a snack as he's not so interested.