Hi! I am actually a fellow (almost) woman and while I understand where you’re coming from, cis isn’t a derogatory word nor a prefix. It’s just an adjective people use for clarity when trans people are involved in the discussion. It comes from the Latin preposition meaning “on this side of” as opposed to trans which is “the other side of”. The word is not meant to degrade your womanhood any more than adjectives like “white” or “brunette” would. Although I apologize if it’s been used that way towards you in the past. People can be shitty.