Dream feeding can be very tricky, I personally hated doing it, but realised it was helping my baby sleep better, you have to spend up to 1 hour encouraging them to feed, gently, so you dont wake them up, you stroke their cheeks, blow on their face, rub their hands/ feet, stroke their hair, jiggle their cheek etc... keep stimulating them with these tactics, also when the teet is in the mouth and they have stopped sucking, pull it slightly out but not all the way and this can sometimes stimulate their sucking relfex, in many ways for a woman its counter intuitive, you feel concerned about feeding a baby whilst asleep, but I combated that by staying with my baby for 45 mins after each dream feed to ensure they were ok, kept them on my lap ready to jump into action if they were sick or choked, thankfully nothing has ever happened, and now I do the dream feed withing 5 minutes and leave the room within 20 minutes, the worst thing that ever happened was my baby had a spasm and she sicked up some milk - but she stayed alseep, wasnt in distress, just managed to cover me and her sleeping bag in milk.but slept on happily regardless.
Try the stimulating tricks to make your baby take more
Good luck