"You are very beautiful."
With that logic, "I'm very beautiful" would be "ben çok güzel". It doesn't work in Turkish. The adjective has to show us what the subject is. Putting "sen" isn't enough.
If your adjective is "X", the conjugation is:
Ben X-im ; Sen X-sin ; O X(tir) ; Biz X-iz ; Siz X-siniz ; Onlar X-(tir)(ler).