Yes, my own mother sexually abused me but later became very upset and punitive about the idea that I was "touching myself," she yelled if I ever said a curse word, etc. These people were mentally ill, they are not going to be consistent. We dissociated when we were sexually abused, and it's just as possible that our abusers were dissociative but to a much higher degree.
You say you don't remember being forced; it is very possible that she groomed you from a very young age in overt or covert ways to accept her molestation and that you just can't recall that right now. Please don't think of it as having sex with your mother; you were sexually abused by her. The entire incest family system is deeply sick. Healing involves listening to and allowing your emotions to go where they please. If you hate your mother, good; you have valid reasons too, continuing to pretend nothing happened can't aide your health.