There is serious mistrust between you and your bf. You seem to think he needs to learn a lesson, as if withholding yourself from him longer will make him more likely to tell the truth the next time. You seem to think there is some ratio of time of withholding to likelihood of truth telling.
This is nonsense! (I was going to use a much harsher word, but you are new and do seem young)
What this shows is that clearly you don’t trust him. You are unwilling to take his word on having reformed his ways. If you believed him, there would be no need to punish him. Since you are punishing him, clearly you don’t believe him. And if you don’t believe him, then your so-called “forgiveness” is another lie.
It is imperative that you do what so many others have suggested and you and he have an honest talk. Sort out what you expect from each other. Understand why he lied and why you should believe him. If you still can’t believe him, then the relationship is over. You may not realize it yet, but you can’t base a relationship on dishonesty, especially when the dishonesty is on both sides.
You’re playing a game, and relationships aren’t games. It isn’t a contest to see who can get more out of whom. It’s not like guys will always try to get away with something and girls have to keep them penned up. That’s not a relationship; that’s a boxing match.
Personally, I think you should dump him now. But you love him soooooo much. So you’ll be learning the hard way. If you guys want to keep this relationship going and make it healthy, you have a lot of work to do, starting with learning how to make yourselves say the truth, even if it is really hard. The truth, they say, will set you free. That’s the risk you take. But wouldn’t you rather know now that you guys can’t communicate than in a couple of years when you’ve spent so much more time with someone you can’t speak clearly to?