Hopefull, I am in the same boat. I honestly don't know why, perhaps I come across as strange or off putting at a guess? However, I have now - almost -accepted that it is the way it is going to be, I certainly don't seem to be able to change it. I am the one person, who finds themselves sitting alone in a crowded room, or who is always the odd one out in any conversation!
I do, whole heartedly agree with Delilia's suggestion, to you to get (borrow / walk / foster) a dog. Whenever, my daughters dog Roxy came to stay with us and I took her into town, people would chat to me on the bus, in the street and in shops and cafes! Its a trip I used to do often, with and without her, (not now as sadly that bus service is no longer running). However, if I didn't make the effort to say hi, talk about the weather etc, with passing strangers, without Roxy in tow I could easily have done it alone and in total silence.
Keeping going, remember, if its of any comfort, that it is their loss as well as yours!