breastfeeding failure

I've been to get my boy weighted today & they are concerned he's not putting enough weight on. I feel so upset that I'm failing my boy. He has put 7oz on in 2 weeks. His feeding has been going good, every 2-3hrs he starts rooting, I'm always prepared with an expressed bottle if we are out & he is due a feed, so he never goes without ever. The only thing now is that he's started going about 6hrs without a feed around bedtime. He's 7 weeks & wondered if that's normal? I've now got to go to a breastfeeding clinic on Thursday. I honestly don't know what else I can do though.