Let me try it another way. I felt a lot of the things you related in your first post. I or some part of me disguised that... made me believe other people were thinking badly of me. I'm not sure now that really applies to your situation since it wasn't necessarily about pleasing other people.
Anyway the most important thing is what you think of yourself. People are going to think what they think and you may not even know their reasons. If you set yourself up to be a door mat there are plenty of people who are going to be very willing to use you for that. You mentioned being a mean person with an attitude.
There is a very wide space you can occupy between the people pleaser and the mean person with attitude. Also everybody definitely does not like mean people with an attitude. You don't have to take sides in these workplace squabbles. You don't have to back anyone up. The only side you have to take is yours. Be true to yourself and the rest of it will fall into place. That doesn't mean everything will be perfect... it just makes for a lot less frustration and confusion.