I'm by no means an expert, but when we had trouble latching I would kind of grab hold of my breast around the aereola area and move the nipple up and down over bubs mouth to get him to open wide, does that make sense? That always gave us a good latch.

You're doing a great job, it will get easier I promise!
That's what I have been doing because a LC showed me how to do that with my last daughter who was a terrible latcher as well. But even doing that with dd2 she won't open her mouth wide. As soon as that nipple gets anywhere near her face she just starts the sucking motion instead. She's done this since the day she was born. Means her mouth is small and pursed and tongue is already sucking so it doesn't wrap around like its supposed to.