I think the biggest red flag is the worry that there might have been CSA in your past. Other than the flashback, everything you mention sounds like a pretty normal variant of childhood sexual curiosity.

Lots of young kids masturbate a lot--so much so that parents often wonder if they itch or have infections because they seem to be touching their genitals constantly. It's not that commonly an indication of abuse. Sometimes it's normal and sometimes it's indicative of an underlying anxiety (like chronic picking at skin, pulling and eating hair etc.) that isn't necessarily related to sexual abuse.

Almost all kids play sex with Ken and Barbie.

Some kids are very perceptive about sex, read a lot and/or pick up cues from their environments (like TV, how adults around them behave, watching animals etc). Intuitive knowledge about sex is also common.

Difficulty potty training and embarrassment about changing in front of people make me think a child has been shamed a lot. Parental impatience and insensitivity about potty training coupled with excessively common toddler constipation can make learning to use the potty very hard. It's definitely an indication of a problem (like some degree of emotional abuse) but I wouldn't necessarily think the problem is CSA.

This is not to dismiss you at all. CSA may have been part of your past. I just don't think that what you're describing sounds extremely suspicious for it especially since it doesn't automatically make sense to you that you were sexually abused based on everything else you know about yourself.