Understanding sexuality as you age

I have to use a throwaway account because it is a very embarrassing subject to discuss. It's very personal and all I want for the moment is your opinion no matter how blunt it is.Case is I am a 32 male, medium height, a little chubby, not all out of shape as I work 12hrs a day on my feet moving back on forth. I smoke cigarettes and I like to smoke pot regularly. I don't drink much at all (I used to when I first turned 21). I don't really exercise and I mostly eat take out... Not really into fast food.Here is my sexual issue...I suffer from performance anxiety... Every time I am with some one I lose my erection and it can be difficult getting it back on... Sometimes I have to lay back and really concentrate on getting hard while I beat it back into position. Guys try to suck me hard again but the truth is that I never really enjoyed receiving head... It would feel good for a while but after a minute it's kinda like "ok I'm bored" and it's always been like that for as long as I can remember... And only once I've been able to cum while a guy sucks me off. And now receiving oral could be an erection killer, as to before where it would just leave nothing but a hard sloppy dick unable to cum because it is simply not my thing.It sounds like a health issue right... But here is the tricky part.I have no problem getting hard when I am alone, I get frisky and load up a movie and I'll be fine. And if I know that the guy I am hooking up with is a total top that doesn't like to give oral I will stay hard the entire encounter... And sometimes even cum while getting jerked off and fucked at the same time. And once in a blue moon I would turn around and fuck the top.I like fucking men, I was a top for most of my 20's but now it feels like such a chore... And I still do, but now it's more mental than physical. Also my desires have gotten dark and some how I feel desensitized from most common sex... Now I get really turned on by being a total sub, or worse anon sex encounters where I do not know who the top is and it is fucking exhilarating.But sadly it leaves me unsatisfied, because some how in my fucked up mind I have ruined vanilla sex and now require a 50 shades method to stay hard...Thoughts?