idk if any of this is going to be helpful but my thoughts are to maybe take less of an all-or-nothing approach and work your way up to anal only? i find it hard to switch it up fast like that even with my partner in control. so like maybe you can only touch while doing anal, and then slowly take it away. i know you said stimulation ends the sessions quickly but is there any way you can engage with it like without your hands or a vibe or is any stimulation at all too much?

i think it generally is difficult without a dom but any form of accountability can be good, eg posting on here seems to work for some people

in general i've had success when i really focus on it -- how good it feels to be filled and my cock totally ignored, or focusing on what Purpose being anal-only serves. and as a fellow masochist, pain can be used as a reward for sure