Struggling to breastfeed

My baby is 11 days old and she was nursing fine at first. At the hospital the nurses did tell me I needed to get her to have a deeper latch, but i told them that I couldn’t get her to open her mouth any wider to do so ( which they never actually gave me a solution for). She didn’t have a problem holding a latch though, and it didn’t hurt anymore than the initial soreness from never doing something like this before. But over the past few days she hasn’t been able to stay latched for more than a few seconds at a time. It makes her extremely frustrated to the point of screaming and clawing at me because she’s not getting food right away. I’m constantly having to fight with her just to get her to eat. I’m pretty sure it’s because she’s not opening her mouth wide enough because even when I use the nipple shield that the hospital gave me (which I don’t like doing because it’s been giving her horrible, blocked gas) she has a hard time latching onto it and just ends of sucking on the tip of it before managing to get the whole thing. I really don’t know what to do at this point, and I’m starting to dread every time she gets hungry. My husband keeps telling me to just switch to formula and be done with it so I don’t stress anymore, but I don’t want to just give up this early on. I hate the idea of not being able to feed my baby like I was supposed to/wanted to. Nothing against people who use formula, but I told myself I was going to breastfeed her for a long time and everyone has told me it’s what I need to do. If I quit especially this early on it’ll make me feel like such a failure. I really don’t know what to do to fix it.

Can anyone please give me any advice on what to do to make this better?