chickenwingprin

I see that there are at least 3 things you can consider:
1. Expand your social circle - this other LYK already mentioned. See posts above.
2. Be more open-minded and don't be afraid to try new things - I'm not saying that you're like this but maybe keep in mind. I know ppl who don't like to do ANYTHING. Often in a large group setting where people are more like casual acquaintances, the group likes to do things like seeing a movie, sing K, eat etc. When you're invited, just go. Try to be less picky about which movie they're seeing, which restaurant they're going etc. Just go. If you keep turning down invitation, chances are ppl won't ask you again. If you're invited to do things you normally won't do (e.g. curling), just give it a try.
3. Learn to be alone. Everyone needs someone, for sure. I find that as you get older, it's more important to learn how to be alone. There're many things one can do by him/herself such as reading a book, watching DVD/TV, shopping, browsing museum/art gallery, hea-ing. Maybe pick up a hobby or learn something new.

P.S. Joining some sports club is also a good way to meet people. I join my friends to play badminton at a drop-in and need up meeting 10+ ppl in the group!