Usually I Like Myself, But Right Now I Don't

Meh...another kind of pity-party post...I would advise everyone to skip over it since it's mostly just my way of getting my feelings out. I'm not looking for anyone to feel sorry for me.
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I feel lonely. Lately I've gotten used to being more social and trying to put myself out there. I like it. I enjoy going to parties and meeting new people.  I actually even enjoy the small talk and sharing information when getting to know someone.  The thing is though, it generally doesn't go any farther than that.  I meet them, we become facebook friends, and that's that.  I don't know what it is about me, but people don't generally want to text or chat, let alone hang out with me, after we meet.  It's not an "eww he's weird" type of thing; I don't believe that people actually dislike or avoid me, but it's more like I become invisible.  It's like I have a forgettable personality, and when it comes time for hanging out or doing things to develop a friendship I get forgotten.  Sometimes reaching out and making an effort works -- I definitely have a few close friends, and others that are becoming closer.  I suppose I should be happy with that.  But it sucks reaching out to people and getting rejected.  Actually, it's not rejection that hurts...with rejection, I have a clear picture of where I stand.  And that rarely happens anyway.  What hurts more is indifference. And it seems like I get that alot.
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I went to a party on Saturday, and it was the type of party that I usually enjoy.  I was feeling extra introverted though, not depressed or antisocial, just introverted -- I hadn't really had time to recharge my social batteries that weekend by having some alone time, and it was showing. Things were getting to me that wouldn't usually bother me...loudness, hugs with everyone, the initial awkwardness of meeting someone new, etc.  I was just emotionally spent and didn't want to make the effort that I usually make at parties.  I had a good time seeing and talking to people that I already knew, like J and M and B and MW and MR, but after that I just felt spent and went off to sit by myself...again, not because I was feeling down or looking for attention, I just felt emotionally tired.  I guess I did feel a little bit down though...there were a couple of people there that I had met before was interested in being friends with, but (as I described above) when I reached out to them, invited them to hang out, etc., I was met with indifference.  So that made me not want to make any more effort with them, or make an effort to meet new people.  One of them came up and started talking to me, though, which made me happy and helped me relax. So maybe there's hope with him, at least. I felt invisible to the other one, though. Ugh, I hate being socially awkward and not knowing what to do about it.