Hi! The first year is super stressful! There are lots of challenges that no-one prepares you for, like sharpening pencils, bathroom abusers, collecting that nurse card from every kid etc etc. I had a really hard class my first year which really hurt too. The start of school is especially stressful, for all teachers I think, because there is SO much paperwork that you need to do and collect from the kids. After the first month, all that calms down and it isn't so overwhelming.
I agree with the idea of finding a mentor teacher. If you don't have an official one, is there someone at your grade level that you can talk to? If not, someone who is in their first 5 years isn't so far removed from that first year craziness that they should totally be able to help you out. Does your district have classes for first year teachers? If so, if you can make it to the first one, I bet you will find many people in the same boat.
My first year I treaded water the whole year. It does get easier! Hang in there!