Hi, earlyninties, welcome to PsychCentral.
When I read your post I was trying to find the "main" feeling or thread/message but I got confused with where to focus. I couldn't tell if you feel more, people don't want you there because you're not a happy person or if you're just a quiet, okay person and people mess with you which makes you worse? Which comes first, the chicken or the egg? :-)
"it really brings me down to where I probably am not nice to people who are fairly nice to me" I get the thought that you wish you could put up with their "teasing" or screwing around with you? What is the nature of their screwing around with you?
I think work can often be like grammar school playgrounds with people trying to be "popular" and backstabbing others at the same time they may feel bad about themselves too.
For me, knowing myself and being friends with myself and supportive of how I am and what I say and do was the best thing I did for myself. I use to be talked about at work too because of the way I am/act but I could go with it, even exaggerate it because I realized it was literally entertaining other people and they were enjoying me and the entertainment.
My 50th birthday party at work where I'm being lei'd by an orange gorilla :-) Another woman I worked with turned 40 two years earlier but was upset about being 40 and when the business owner's daughter wanted to roast her, I sacrificed myself and my 50th birthday in her place!
Look hard at the people who are fairly nice to you and try to start a little interaction with them, tell them a little about yourself/your interests and/or struggles. If we move inward on ourselves, we can only go in so far but moving outward provides more space and opportunity. Use some of your limited energy getting to be friends with yourself and a few others and that might get you more energy. If you talk to one or two people, they're likely to help you when others try to mess with you or, if you can "put up with" or make a little bit of fun of your not talking (pretend to be a mime?) a bit of good humor will get them to not mess with you as much or as often?