Thank you so much for sharing! I have a couple questions that popped up reading your reply. I know Sam might respond as well when she is on shift.
To start I just want to say, I had a really similar experience engaging with sexual content online when I was younger that traumatized me and it is TOUGH. I just want to validate your experience dealing with that because I know it creates intense nuance for looking for sexual content now as an adult.
One thing I wanted to discuss is your asexual identity! How do you define that for yourself? Because asexuality, like all sexualities, exist on a spectrum that has a lot of different experiences in it. I would encourage you to check out this piece because it really dives into a lot of that nuance Just the Basics, Ace: An Asexuality Primer
.You mentioned that your guilt that comes from watching porn is related to feeling like you've done something that "directly contradicts your identity." That's a heavy statement and I can imagine that it adds a lot of stress to this situation. I want to encourage you to really try to define what your identity is TO YOU, not to anyone else, and encourage you to try to expand the boundaries of what fits under the definition of asexuality. I personally fall on the asexual spectrum and enjoy many of the things you've mentioned; that doesn't change the fact that sex is not my biggest priority in relationships. It just is something I sometimes enjoy.
It makes sense to me that written and drawn erotica is more appealing to you because more often that not that involves some sort of focus on the relationship between two characters where you learn about that dynamic and it is not just two strangers. It's a good thing that you can identify stuff you do enjoy and you feel good about engaging with. I think continuing to find stress relievers that you feel good about and enjoy is going to overall decrease the stress levels you're that fuels the behavior you're not feeling good about.
I am not a therapist or a sexologist (both professions I would recommend you seek aid from!) so I can't tell you why I think you're doing what you're doing. But behaviorly there are steps you can make to protect yourself from harm and overall aid your relationship to sexual content. I think letting yourself feel sexual desire is not a bad thing. The more we try to contain emotions and physiological reactions the harder they can be to manage. Giving yourself permission to feel what you need to feel is really important. When we label thought patterns or desires as inherently "bad" it is going to cause us to fixate on the feeling more because we think it's bad. So maybe a component of your fixation lies in your emotion around your sexual desires. Sometimes we seek out behavior/content we know will harm us. It's a really frustrating reaction for us to have but its not abnormal or something you should feel shame from. Rather, identifying the harm and actively trying to change that behavior and possibly interrogate it with a professional mental health practitioner is a good response.
I know this doesn't answer all your questions but I would love to hear your thoughts on some of the things I've mentioned. Overall, I want you to try to have a little more patience and understanding for your body and its reactions. You are not wrong. Your emotions are not "wrong". You are just a human trying to figure out this wild world of sexuality and media. That's a big task for all of us. So be kind to your body as it finds its way through this.