7 week old refusing to nurse unless I have a let down

I've been bf since the start with the same issues many women have, improper latching. I met with a lactation nurse and we corrected the problem. My daughter has been doing great. I have a difficult time pumping anything, but I'm home with her all day and she eats plenty. She's now 7 weeks, and about almost 2 weeks ago now, she refuses to stay latched if the flow isn't fast enough for her. She will cry and pull and unlatch multiple times no matter which breast I try. Once the let down occurs she's fine but once it slows again she returns to pulling on my nipple and unlatching and trying to relatch but it's a shallow latch. I'm not sure what to do. She was introduced to a bottle at 8 days old because she was sick and they wanted her getting every ounce she could. Once she was better, she has rarely had a bottle. If it's nipple confusion, would it happen so much later? I feel bad because at times the let down doesn't occur right away, and she won't stay on long enough to suck to create the let down. She has plenty of pees and poos each day, and last appointment her weight was great. I don't understand what changed and how to get her back to before