Is this normal?

I know everyone seems to think supply issues aren't necessarily legit. But is it normal that my almost 8 week old baby feeds every hour or two and every feeding has to come from both breasts and lasts at least 40 mins? I'm convinced he's not getting enough milk. He's constantly on my breast   And no it's not a growth spurt this has been since day one and has gotten more frequent and longer as he is getting older. The doctor we saw when he was a month and we don't go back until he's almost three months old (weird I know. But the doc said that's fine she's just booked solid) said that his weight gain was fine in a month... She even said we shouldn't supplement with formula. But if what my home scale is saying is correct (I weigh myself and then me holding him) he hasn't gained even a pound in almost a month. I am beginning to think I legit have supply issues and should prob stop trying so hard to breastfeed him.  My question is; Is it normal for your baby to feed for so long so frequently at this age?