Been exclusively pumping as baby had latching issues was in nicu for week and got used to bottles became lazy

Now 8 weeks old we tried nipple shield and wasn’t working for long. He would get annoyed. Last time I tried was maybe 4 weeks ago and he made me bleed and the other boob leaked all over his onesie… gonna try again tonight… any tips? How long should he be on each breast? Thank you! Wish me luck! My pumping took a dip today only pumping about 90 a session (every 2.5-3 hours I pump) thank you !