Well, according to /r/nofap porn is the root of all evil...

Sure, and according to /r/TheRedPill feminism is the root of all evil. And according to /r/Paleo grains are the root of all evil. /r/NoFap is a community of men that have convinced themselves that masturbation is the source of their problems. And like, if you feel like masturbation is seriously impacting your life then go ahead and cut back, as with anything else. But that place is full of ideological pseudoscience and anxious masculinity; I wouldn't take it all to heart. And your problems don't sound to me like a masturbation issue.

I'm gonna go out on a limb a little here, but I'm getting the sense that a bigger issue here is that you don't feel much connection or trust with anyone you're fucking and it's leaving you really anxious in bed. And that's not a problem with you, but likely a problem with how you're going about meeting guys and the speed at which you're moving with them.

But that might be a little projection. As a bisexual trans woman, I've definitely always warmed up slowly to men; even pre-transition when I was in more of a femboy gender space, it was hard to open up and trust male partners and it definitely made the sex a bit strained and awkward. It took me a while to learn that I just had to take longer to build trust with them, and that while I'm generally geared toward promiscuity I just need to take it slower with guys. Even if they were cute and I was very attracted to them.

I have tried twice, and it was painful. But I am willing to try it again, I just haven't found someone who I really trust for this.

Yikes. So the thing with bottoming when you don't do it all the time is that you need someone who is patient and knows what they're doing. An inexperienced or inconsiderate lover will hurt you at least a little bit. But it doesn't ever need to be painful.

The other thing you need is really good lube and plenty of foreplay. I get a lot of mileage out of Pjur's Analyze Me lube. It's silicone based, so it lasts a long time. Consider using disposable nitrile exam gloves when using it, as otherwise lube gets on his hand and then next thing you know it's on your sheets and in your hair... Of course an ex partner of mine really loved oil-based lubes like Elbow Grease. It was ultimately a texture thing for her. I'd encourage you to experiment on your own.

Bottoming will definitely make you a better and more considerate top, though, so I'd always recommend it.