People just look through me + I offend people unintentionally

I was never diagnosed growing up and finally been diagnosed well into adulthood.

I have had a very traumatic year and in the process of being treated for that, I was diagnosed with autism. I was told by the doctor that it is not uncommon for women to be diagnosed later in life.

I have a very hard time making friends. People just look through me and I am often mocked and ridiculed for things I say and often I cannot work out what I said that was wrong.

Also, sometimes I say things that I believe to be inoffensive and harmless but people get offended. I don't know what to do about this? I absolutely hate conflict and do not want to hurt or offend anyone but this is hard when I cannot figure out what I said or did wrong.