Building muscle exercise weights body building?

[S M]

Hello, I am 18 years old and have been training hard for about three months. I am at the point that I don't get sore anymore no matter how hard I work. Maybe a little sore but nothing like when I started. There was a time that after a good arm workout I was lucky to comb my hair the next day. Question is, if i am not getting sore am I still building muscle? Thanks