Not feeling it

Lately, I've been feeling very unmotivated and not my usual semi happy self. I've been feeling rather alone and like all my friends will eventually leave me. The days are just flying by and I feel like I don't have enough time to accomplish everything I want. Everyone else my age seems to be happy, getting married, having kids, along with many other accomplishments. I guess I feel like I haven't done anything worthwhile with my life. I am in need of some new friends because I feel like all of mine have moved on and they just don't have time for me.