Pregnant and Breastfeeding

Chelsea
I've just fallen pregnant again, and I'm still feeding my 1 year old but I think my milk is beginning to dry up. I still have a small amount but he now feeds for hours trying to get more and it's starting to hurt as no matter how hard he sucks he's not getting much milk.
He used to feed to sleep but now that's becoming very frustrating as he's not getting the milk out and he's becoming frustrated. Does anyone have any tips for weaning?