What exactly are p-subs?

I'm pretty new to NoFap, but I feel like I don't fit in very well here for a lot of reasons. The biggest reason is that I have no issue with actual porn. I haven't had any sort of urge to look at it, and even when I was in my fapping days I wouldn't get much out of traditional porn sources. My vice is snapchat. Sending and receiving dirty pictures from many girls, and talking sexually very often. In a sense, I relapsed this past weekend, if it counts as a relapse to talk sexually. My question is, how is this considered a p-sub if they are actual girls that I am doing this with? Most of which I have hooked up with in the past. Or is this more of a sexual problem? Like hyper-sexualization (or whatever the correct term is)? I've been very sexually active with very many sexual partners for most of my life, and I want to get the most out of my reboot, but I would appreciate some clarity on this issue. I've had no problems with ED, but I have experience DE from masturbating too much. Also, what are some other examples of p-subs? Thank you very much for your help.

 

Thank you for your reply. That's a good way of putting it. I know that I will greatly improve if I eliminate fapping to porn, but for the most successful reboot possible, I know I need to avoid lust.