I feel like I'm being thrown into the deep end with surgical cases above my level at times

Pgy-1 categorical surgery intern a community hospital. I get a solid amount of operative experience for an intern, I'd think. 120 cases so far. Much of this is varied, but some of it is definitely above my skill level.

I've only done a few 'lumps and bumps', and today my attending asked me to help with the dissection for a basilic vein transposition. I've literally only read this anatomy in books, and by help with the dissection he basically meant do the procedure and he'll tell me what layers to cut and close while he's with me. I started the dissection, and was gentle/careful as I could be going through the layers, he ended up saying that I'm too afraid with the bovie and that I need to speed things up, and if I hit a vessel not to worry because he'd fix it. So I sped up slightly, Anyway, to cut the story short I end up nicking the basilic vein with a bovie and get 100-200ccs of blood loss (felt lile 500) that my attending controls, fixes the hole I made w/ prolene, and we do the rest of the procedure uneventfully. Patient went home and suffered no ill effect. I end up having to change out of my gown and scrubs because I'm drenched in blood.

Like I feel like I'm a bit over my head, I'm real I don't quite understand the anatomy perfectly, and the concept of doing a good and safe dissection & through what planes I can cut/divide, is still foreign to me. I'm no expert in dissecting. He did teach me a lot during the case and didn't yell at me/etc, and i feel like i can do a little better the next time and not fuck up as bad. But i genuinely think that I should be doing simpiler cases to get the hang of the bovie, when to use mets, how to manipulate tissue, etc.