I can’t make myself cum

I have been fingering mussels for almost 2 months and I can never finish. I’ve read things on the internet and I understand what to do but every time I end up getting way incredibly sensitive. Like so sensitive I can’t even lightly touch, even through close. It’s just like too much. Idk if I’m doing something wrong or what but it’s getting annoying and I’m worried I will never experience cumming