I have a big, healthy 9mo girl in my child care who is exactly the same. She took a bottle from me fine before she left for the summer (both parents are teachers). Now, nothing.
After much consultation with parents, child care food program, drs, etc, we have decided to keep trying a cup/sippy daily, but forget the bottle. We would try to wean her from that in just a couple of months anyway... She gets breastmilk mixed with her cereal and some fruits/veggies/proteins. I keep track of amts for Mom. Lately I have been able to get her to take
1/2-2 oz from a cup/straw. Everyday is improving slightly. She still nurses in the am and evenings. Mom is not nursing her at night...even when she fusses. She does not need it at night...and your guy probably doesn't either.
Breastfed babies will get what they need from mom. They will get it whenever you give it to them....if you are willing to nurse around the clock, he'll take it! Doesn't mean he needs it. If you nurse in the morning and evening, your milk will change to give him what he needs. He will be fine through the night. Might not be thrilled at first, but will not starve!
As long as he is happy during the day, having wet/poopy diapers, and drs are satisfied with growth, there should be no worries!