Hun,
Your bub sounds exactly like my bub at that age. I can honestly say that BF has been the hardest thing out of having a new bub. It's only the last few weeks things have become easier. I too used the shields, my supply dropped and bub never seemed to be getting enough from me' so I was topping up after most feeds. I decided to get rid of the shields & what do you know bub can attach fine now and my supply has increased & she only gets about 40ml of formula at night, sometimes she doesn't need it.
Noone tells you how hard BF is to establish, I just envisioned my bub feeding angelically at the breast but in reality it wasn't like this. I found for my daughter she had to learn what to do. I had to learn & so did she.
Hang in there, offer the boob every feed, like you did today, if she gets a little bit of practice each time she will get the hang of it. Don't give up the first 6 weeks are by far the hardest and by 2 months things will be' so much easier.
Do you try squeezing your boob to make it a bit narrower so that she can get it into her mouth? Maybe she is having trouble getting enough boob in her little mouth.
Perhaps you could try syringing a little ebm into her mouth whilst she is on the boob.
Like my little girl she may just have to learn that she has to suck to get what she wants.
Good luck Hun, you're not alone, it is really tough but you can do it