If there are opportunities to volunteer or get involved in activities or groups at your Parish....do so....you'll find it's easier to make friends in smaller group settings.
Maybe inquire at the Church office regarding groups and activities going on in your Parish.
I'm guilty of attending Mass and not necessarily reaching out to others in a fellowship aspect, because I get involved internally, with prayer and reflection re: the readings and the homily, etc.....and sometimes when leaving Church, I'm still in my "zone"......
However, I'm alot more friendly and approachable at Church social and lay ministry events and I enjoy meeting people and making friends.
So just because you seem to find yourself alone / lonely at Mass - don't give up on your fellow parishioners....try getting to know them outside of Church. :thumbsup: