how much should I be pumping at 7 months?

Carly
I'm a BF mom who works full time and my LO just turned 7 months. I feel like my supply has dipped some in the past couple of weeks and just wondered if that's bc he doesn't need as much and it's normal, or if I should start being concerned and try to get it back up? Its only dipped a couple of ounces but it still has me worried. I might also add that my period returned for the first time this week- but the dip is still noticeable and it's been almost a week since I started. 
Lately this has been my schedule:
7 am - bf him before work
11 am - pump anywhere from 5-8 ounces
3 - pump 4-5 ounces (this session is always less)
7:30 - Bf before bed
Anywhere from 2-4 am: BF
He also eats solids 1-2 times per day. 
He gets 2-3 five ounce bottles while I'm away and usually seems satisfied when I return from work in the evenings. However, with this dip in supply, I'm not able to pump 3 five ounce bottles everyday. I'm lucky if I can get 2 and a half.