I have never felt letdown ever and my boobs have never hurt, felt full etc and I think I have leaked twice when DD was 9 weeks old and starting sleeping through the night. I have never had much milk when expressing, it would take me 2 days to get 100mls!
DD is now 7.5 months old and her main source of food is breast milk as she is not a fan of solids and is nick named The Clam as that's what her mouth does when food comes near here!
I just keep believing in my milk, I do lots of skin to skin.
You have done well it's sure harder than I ever imagined!
I would keep putting bubs on the boob if that's what you want