I gain weight in summer and lose it in the fall/winter

I’ve thought I gained weight recently but I just weighted myself and turns out I gained 8 pounds. Last summer I was 152, I went to 138 at Christmas and now 148. I’m 17 and 5’7. Is this normal, do I look okay? I see myself 10+ pounds more than I am. Everyone says I look skinny but I just can’t see it. I’m thinking about going on diet pills or something. I just don’t know what to do anymore. Please help me

This is me now

A few months ago

Around Christmas