Pregnancy does reduce your supply. Some babies will happily feed through the drop, and others get frustrated and give up. It sound like your little one is quite happy to keep going.

If you are happy to keep letting him take the lead it's fine to do so. He will most likely still be getting some milk, and the milk he's getting will have a higher concentration of nutrients and immunity factors. This is nature's way of providing extra protection as the baby start to grow up and starts reducing feeds.

It can also be very helpful to have a toddler who still bfs as it does provide them with a lot of comfort and helps you to settle them easily when they are upset. If he continues to feed through your pg, it can be a way for him to cope with the changes involved in having a new baby in the family. Tandem feeding (when you are feeding both a baby and a toddler) can also help mums avoid engorgement in the early days.

Best of luck with it!