Breastfeeding while pregnant

Hey ladies. Has anyone nursed while pregnant? I’m currently doing it my son is three I only do it at night he likes the routine and I’m available so I wouldn’t stop for myself until he is ready. However, I noticed if I squeeze my boob myself nothing comes out :( I’m worried nothing is coming out for him. I know he does the routine if nothing is coming out he hasn’t stopped sucking at least lol.

But I’m just curious first time feeding during pregnancy so looking for advice :)

Thank you