Scared I abused my much younger sister when younger

Just to clarify I’m now an 18 yo male. I feel like I might have some ocd traits around this as Ive been obsessively anxious and worried about this for about the past six months since the memory randomly popped into my head and any time I feel the need to alleviate my anxiety I check forums such as this with people with similar stories, but I’m also aware that this is a genuine issue I should be worried about and I need some perspective and advice on how best to approach this.
When I was just reaching puberty and discovering porn (around 11 years old), I found I became interested and fascinated with porn such as femdom and facesitting. Around this time I started a game/joke with my much younger sister who was about 4 at the time where I’d lift her up while she tried to get a teddy or something from the top of her wardrobe, I’d sit her on my head while I lifted her up so she could get the teddy and tease her about smelling etc. With the interest in this porn and this behaviour with my sister intertwined it piqued my sexual interest and so I’d instigate this more, pretending to smell her butt and tease her about it etc. Sometimes she found it funny and started the game and other times she didn’t want to if I started it, in which case I always stopped. This behaviour happened a good few times over a period of several months and stopped when I was around 12, not any older than 13. To clarify, I didn’t touch her genitalia, didn’t make her touch mine and we were never naked in this situation. At this age I wasn’t aware of what could be categorised as abuse, thinking that it involved pain, screaming, etc and I thought this was simply more embarrassing than anything, but never felt it could harm my sister. I grew out of this behaviour and completely stopped coming into my teenage years but I hadn’t given it a second thought until it popped into my head over a month ago, and from then on I have been filled with complete paranoia, anxiety, and have been depressed about all of this and fearful of it hurting my sister and ruining her life as she grows older (she’s 9 now, turning 10 soon) and that it will eventually come out and ruin my life, my girlfriend will leave me, my family will disown me and I’ll be arrested. I am honestly not attracted in any way, shape or form to children, and have no desire to do this again, and haven’t for years. I don’t know what went through my head at that age but just know that I had an interest in that type of porn and felt extremely curious about it, and I don’t think I felt any attached any sort of moral boundaries to this. What bothers me is it took me so long to grow out of doing this and i cant view it as a one off mistake. I feel so scared about this, and haven’t told anyone. Please can someone offer some sort of perspective or advice

Edit - as of now, my relationship with my sister is completely fine and she is in no way scared of me