S.C.
How old is baby?
I would try to keep nursing and stop supplimenting altogether. I always felt like I was drying up, but my babies were always full and satisfied except during growth spurts of course! But God designed our bodies so wonderfully that when that happens we make more milk!
BUT if you are in fact drying up, you can tell by a baby that is not getting enough to eat. Less wet/poopy diapers, very fussy and not gaining weight.
Oh, and the hand down shirt in public? I have 4 kids and only my daughter has really done that, and it was a comfort thing (that I stopped out of embarrassment) for her AFTER I weaned her...