Breastfeeding and sleep


I am exclusively nursing my baby girl. She is 11 weeks old now and she is A SLEEPER (finally)! She routinely goes 4 1/2hrs at a time, last night she went 6 1/2 hrs straight! Needless to say when she did wake up to eat I was so full it was painful when she latched on. I WANT to be able to continue nursing her and am afraid that these long spurts of sleep will affect my supply. It hasn’t seemed to yet, as she will nurse a good 20 mins on each side and I can still pump between 4-6oz when she is napping and I need to pump. Has anyone else had success with letting their LO sleep and still maintaining a good supply, or should I really wake her every 3 hrs to eat??