bella I had something similar and I found the wind was difficult but I got myself along to a breastfeeding cafe on the referral of a lactation consultation and thankfully was able to meet some excellent midwives. I really think it would be helpful if you see someone who is experienced and can see if there is a problem.
I think that your post means that you are concerned, but as philbee says the charts can be unfair - and I found them to drive me nuts - but checking whether your baby is alert is key.
Anyway the advice I got really helped me - and resulted in better weight gain and lots more filled nappies.
My latch was checked and some improvements were suggested.
They watched me feed and also observed my milk supply and gave me some tips for improving both.
I kept going with the burping and try burp before a feed as well as during.
If the baby fell asleep during feeds then I would try keep him alert.
Waking baby through the night - so as not to allow the baby to go 7 hours without a feed - this was to get the fatty milk in - this was the biggest difference. Also during the day I would feed every 2-3 hours, hard work but worth it to see the weight gain.
Expressing after each feed (although I was so tired I found this hard and could not always do it) but this was suggested to keep/increase my milk supply going, and then say once a day - then after a breastfeed I would get my DH to feed this to the baby.
All such hard work - but worth it for me, and once the weight gain picked up I could relax and now the baby is back to long sleeps during the night.
Good luck and let us know how you get on