In the first weeks it seems like they're never satisfied - count the nappies, that's the best indication.
If you feel your nipples are sore, then perhaps seek help from an LC or ABA counsellor to ensure the latch is right. Sometimes it can be just ever so slightly off.
It's a common misperception that our breasts are like jugs that need to be filled before we can feed, but you don't have to 'wait' for more milk. Your breasts will make it as needed. When you're feeding frequently your breasts will feel emptier, but that does not translate to low supply. In fact, frequent emptying of your breasts is the absolute best thing to boost supply.

You're doing great, really, by following your baby's cues and feeding on demand. Sometimes it may just be comfort he wants, but that's ok too. Take care of yourself