Breastfeeding problems!

I'd really appreciate some advice. My DS is 4 weeks old, he was 3 weeks premature and we had some problems at the beginning where he had to go back into hospital for an infection, jaundice and low weight. In the hospital as he wasn't feeding well they told me to breastfeed, then express and then top him up with formula to get his weight up. We came home and continued that regime of feeding, I never seem to produce enough milk for what he needs. I went to see a breastfeeding consultant and she said he has a poor latch and is lazy so suggesting continuing but also expressing between feeds. He's started getting trapped wind (he is burped during and after every feed) from the bottle feeding so I'm giving him Infacol but that is making him constipated so I'm also giving him 30ml cooled boiled water (NHS advised) between feeds. So that means that the feeding regime is:
Give him the boiled water (he won't drink it if given after a feed)
Give him Infacol
Breastfeed (40mins max)
Give him any expressed milk I have
Top up with formula if still hungry (he always is)
Express
Then express again an hour later

It is absolutely exhausting and when I'm meant to be sleeping (when he is) I'm expressing or trying to eat something.

Has anyone else had to do something similar and if so how did you cope? I want to persevere because in the long run breastfeeding is much easier than formula and I'm hoping at some point he'll exclusively take the breast but I can't see the light at the end of the tunnel...