Worst thing I've ever done

I have been feeling immense guilt and remorse over something I did years ago. I was in the lounge of the place I was living in at the time and my friend's kitten was on the couch, doing the suckling thing kittens do to the couch/blanket. I don't know what I was thinking, but I feel absolute disgust at what I did next. I felt curious about what the sensation of the suckling would feel like, and I remember seeing this clip on tv a few years prior of a woman letting a cat breastfeed off her. It could have been a combination of curiosity and the tv clip, I'm not 100% certain. I knew it was wrong, I felt wrong about it but I was horny and curious and I let it suckle on my nipples. I remember feeling pleasure from it and getting off on it, but feeling ashamed. I felt guilty, and quite low at the time and I was sexually inexperienced, never having even kissed a boy or anything. I had never felt attracted to animals and the thought makes me cringe now and it would have back then, too. Like what the heck was I thinking? I've never told anyone and I never did it again. I put it down to sexual curiosity and idiocy as it was an isolated experience. I knew at the time I wasn't experienced or a happy, good decision making person. I regret it so much. I think I was able to suppress the memory because of this. I also knew I wasn't attracted to animals, like I wasn't thinking of the kitten as I was doing it, as far as I can remember. I'd never looked at an animal and wanted to do anything sexual to it. The only other thing that comes to mind is when I was 9 or 10 and I let my dog lick the inside of my mouth because I thought it would be like kissing. I honestly believe that was a stupid thing I did as a kid and as soon as my parents found out (like it didn't happen for long) they told me off because they it was dirty, the dog's mouth had goodness knows what germs, etc, etc. I then felt gross and ashamed and I did know that animal human contact of that nature wasn't right.

Back to the kitten... I feel so dirty, and so ashamed, and I feel so bad. I cannot believe I did something like that. I have been obsessively researching what is normal sexual development for adolescents and children and I've found a lot of stuff online. It's been quite disturbing to read cases of bestiality but I feel like I need to know if what I did was normal for an adolescent. I guess I can come to the conclusion that it isn't normal, but it happens. There were stories of people like me, who have felt guilty over it years and years later after being triggered and felt horrified at what they did. Here's the kicker though, I wasn't a young adolescent when I did this. I had just turned 18 by a few months. I am 26 soon. I feel like I should have known better. I'm twisted.

You aren't twisted. It was a little odd, sure, but you did not violate the kitten, nor would it have found the experience distressing. It sounds like it was motivated by thoughtless curiosity. I honestly think the best thing you can do is do some work at a rescue shelter or adopt a cat if you don't already have one. It is clearly not an experience you will repeat

It is an act of bonding with a baby animal. It likely brought some comfort to both of you and satisfied your maternal curiosity. It was an experiment. I see no true perversion in it. There was no devious intent or harm done.
I would just acknowledge that you did it and put it behind you.

We had a litter of kittens whose mom had mastitis and the vet said that if she breastfed her kittens, she could die. That mom-cat's instinct to breastfeed her babies was incredibly strong. She jumped 8 feet to the top of a shelf to reach them and feed them. I tried wrapping her torso to keep her from breastfeeding. It was just an incredibly strong 'do or die' drive.
We bottle-fed the kittens until they matured enough and the mom recovered. It helped the kittens bond to humans and us bond to them.

I've had cats that were likely taken from their mom too soon. They would suckle on my shirt buttons and use their paws to knead my shirt like they were breastfeeding. Some would leave behind a saliva spot when they fell asleep on me.
I think that it is a beautiful act between the baby and mother that defines who we are to the cat. They look up to us as a maternal image for food and care.
My parents took a picture of me sleeping in a crib with kittens around me, so I've been a cat-person for a long time.