Having a 30's crisis and missing my twenties...

Hi everyone. I don't know if someone relates to this but I feel like having a 30's crisis right now. I'm 35 but I don't look like or feel like 35, I feel and look like having 30 now and feel like having a crisis between the transition from 20's and being younger to a more mature age and different needs.

I'm in a stable relationship with my fiancé and have a stable job but I feel so bored most of the time. I miss soooo much going out with friends, playing guitar on the beach, having fun, those things. Now all my friends are married with kids and have their adult lives. 5 years ago me and my fiancé also went living in another country and I was so excited and thrilled with the possibilities of having different work experiences and meeting different people. Now we returned to our hometown and although is good to be back home, I feel stuck. Everything is so stable and predictable now. And of course, the next step after marrying is having children and take care of children like everybody else...