POCD: Did I molest the child?

Hello.

I am feeling guilty right now. I have a younger half-brother. I remember that once my stepmother asked me to bathe him. I had POCD even back then and I thought that bathing him would prove me that I am no pedophile and saw it as a kind of exposure thing. I asked my stepmother whether I should use a washcloth or my bare hands and she told me just to use my bare hands so I put the soap on his body with my bare hands including his private parts. Then I washed the soap away and put soap on his body again in the same way, then washed it away. Now I am feeling like this was wrong, I think I should have used a washcloth or asked my brother to put soap on his private parts himself. I feel like I had bad intentions. I didn't do it to arouse me and wasn't aroused by it at all but it feels wrong like I used my brother for testing or proving something.

What do you think?

Sounds like you just washed your brother, and now like all themes of OCD you're looking for it being a sign or a reason for things.
Neither of which is true... you washed your brother, and now you're over thinking that fact.