thank u for all replies, good news is my boy is young, things change everyday, I even don't know what I did makes the change, I mean he can latch on L as often as R now (most of the time). don't know what will happen in the future, looks like my supply is increasing, so I did reduce the bottle feeding and hope thing stays stable.
I totally agree that mix feeding can cause confusion, but I do want to keep bottle so I can have some naps in daytime, my boy doesn't sleep well at night, and my Mom is here helping me, when I have the nap Mom can feed my boy with bottle, and it's not always formula, sometimes the milk I pumped.
one question is how often I feed my son at night? mine, that's another story, or I should say another challenge, I just don't know how Tracy (the author) made it, she says in the book that 3 hours is interval and only need to feed the baby once all night long. maybe they r right, they always make it sounds so easy in the book. my son would wake up every 40mins~1hour in the worst case, I don't feed him everytime he wakes up, it depends on the interval, if it's over 1hour then I feed him.
I have to spend lots of time on this forum to look for help, good thing is there is always response, it makes me feel not lonely.
thank u everyone again. switching to EASY to see if I can find the help with night sleep interval.