Baby won’t stay latched

My daughter will be 3 weeks old tomorrow and we are still struggling with breastfeeding. She’s gaining weight really well, but each time I feed her, she struggles to stay latched, constantly popping off and then getting frustrated and then I have to help her latch again. Over and over and over. She did have a tongue tie, but that has been corrected already so I just can’t figure out what the problem is. Sometimes it will take us 10 minutes just to get a good latch and it makes me so nervous to have to breastfeed in public. Anyone else have this issue or know what I could try to help her latch better?