Child sexual development- curiosity is normal. However, the object of it can be wrong. That's why I used misplaced sexuality term (probably not the same in English, sorry).
Your mother sexualised your childhood and blurred the boundaries for you. Watching your mother undressing is not a way to get love from her/be close to her- or anybody for what matters. If I were you that's what I'd address in my therapy. I could be wrong though.