Nursing a toddler while pregnant

I think my toddler hates me now! I know I'm running out of milk or it atleast tastes different because he normally uses the boobs as comfort but they can't comfort him much anymore ... he's up for hours at night because I can't comfort him back to sleep and it makes me so sad.. not to mention exhausted. I'm 5 weeks 1 day so I'm supposed to be tired anyways I guess. I'm thinking he might self wean before the new baby is born .. which would be nice but also sad because I'll miss the bonding. He will be turning two right around the time the new baby arrives. Anyone else experience anything similar? Would love to hear others experiences with breastfeeding while pregnant.