Bochur,
Your struggle makes perfect sense because you’re only half way there. Although you’ve stopped acting in a negative way, in order to feel good about it you have to fill the void with something at least as stimulating and satisfying, otherwise the doubts and thoughts of “going back” will give you no rest. The answer is deceptively simple and you already know it: increasing kedusha and ruchniyus is the only way to fill the void. You say
ruchnius seems so far away and vague to me when I think about it
– this is what needs to change. But how? The Y”H has a big head start over ruchniyus – he starts his relentless sweet talking as soon as we’re born, and pursuing what he wants is instinctive and appeals to our basic and base physical nature. Ruchniyus on the other hand, takes maturity and hard work. If it didn’t, we wouldn’t be “earning” a reward for pursuing it, so in a purely intellectual way, this makes sense. Amid the worldwide economic crisis today, it’s clearer in this day and age than at any time in recent memory: if it sounds too good to be true, it probably is. We can’t earn the eternal and unlimited return on an investment in ruchniyus without a lot of effort. But since the benefits are not readily apparent, unlike the pleasures offered by the Y”H, how can you convince yourself of this in your heart, on an emotional level?
The first step there is self knowledge. A Baal Teshuvah like you is already far ahead of a “FFB” in this regard because you’ve already made a conscious decision after weighing the different paths in your own mind to become frum. I must confess that this process is beyond my understanding and experience and I truly admire people who do this. As an FFB, I had the opposite problem – how to do the very same things I’d been doing my whole life…but for the right reasons this time. So I’d first ask you to remind yourself (and please share if you’re willing) why you became frum in the first place?
The next step is to identify any and all causes for emotional pain. As “me” asked, are you going through a difficult time right now? Are there things that bother you on a routine basis that you can’t overcome? When you acted out, what were the circumstances? What precipitated the urge to indulge? In the beginning it sounds like you got sucked in by the “open attitude” of your parents, but if you’re experiencing anxiety when trying to stop then it’s gone beyond that. Acting out seems to have evolved into a soothing mechanism for some type of pain which is why it’s difficult to resist giving in. No one wants to be in pain and we instinctively do anything we can to avoid it. So try to identify the sources of emotional pain and examine them to see if a misperception or two may be behind that door.
Once you're aware of what gets you down, the stage is set, you're ready to move UP. Find any part or aspect of Torah that excites you. Whether it be Halacha, Hashkafa, Chumash, Nach, Mussar, etc., whether the best medium for you is a Shiur, a Chavrusah or meditation in the forest – it doesn’t matter. The key is that it speaks to you, to your heart.
Let me know what you find!