By 7 months, I think my baby was eating a number 2 jar at breakfast and a number 2 jar at dinner. Occasionally I mixed cereal with her jars, but not often because she never seemed to need it. As far as her bottles went.... she was drinking between 4-5 ounces at a time.... lets see.... she nursed first thing in the morning, around 6, then a bottle at 9, 12, 3, 6, and 9.... something like that.... depended on what time she actually woke up.... but she usually ate every three hours. So doing the math, she would drink between 20-25 ounces a day. And she's been sleeping through the night since 3 months old.
All babies are different. My oldest took 8 ounces at a time by 7 months, eating every 3-4 hours, plus she was eating 3 number two jars a day, AND she still ate in the middle of the night! My middle child barely could finish 4 ounces at a time, ate every 4 hours, would barely finish two number one jars.... and she also ate in the middle of the night.
I would try feeding him more. If you absolutely can't pump any more than what you are doing (and I do know it's hard!), you might try adding formula too. You might also try giving him more food, although I've found with my baby, that if she misses a jar of food during the day, she still usually sleeps through the night, but if she misses a bottle, she's up and won't go back to sleep without one (sometimes it takes me forever to figure that out in the middle of the night too!).
Hope this helps!