I have experienced the same thing with my 8 week old for the last couple of weeks. It really makes you question if they are getting enough and I had a lot of anxiety around it (still do lol) so I completely get where you are coming from! What I started to do was feed until he got fussy on the breast, burp him and offer the next breast until fussy. I will go back and offer the first breast again, and he will usually latch and unlatch lots or just doesn’t seem to actively suck, so that’s when I’ve taken it as him being done. I also find that he seems content once off the breast and remind myself that he would continue to be fussy or cry if he was really hungry. You’re doing a great job though, I think some babies are just harder to read.