Breastfeeding mamas!

My 10 week old was early 6.4 weeks. I had a pretty fast flow early on and he would feed for about 10 minutes and spit up and still gain weight. Slowly we started to work better together and he would feed anywhere from 15-30 minutes and he’s been gaining weight. Suddenly in the last few days he’s either been cluster feeding every hour or goes for 4 hours and then only feeds for 5-10 minutes. I’m worried something’s wrong.

I know I should go in and weigh him but I don’t have access to a scale at the moment. Are there any other indicators that he’s still getting enough other than by tracking his weight?

He seems satisfied and if I try to nurse him more he just fights it or spits up. He also went his first 6 hour stretch over night. Ate for 15 minutes before bed and woke up only to feed for 5 minutes.