From his point of view he wants to work out how to have sex with with you.
Once he's had sex with you a few times, he'll have been there and gotten the T shirt. At that point he may stay with you in an exclusive relationship for a while longer. Or he may not. He may have sex with other women within a couple of months of having sex with you.
He is more likely to cheat on you if you go ahead and have sex with him.
He will say whatever he thinks it will take to unlock your chastity.
His actions show that he doesn't regard the 2 of you as being in an exclusive relationship. This would be OK if he were totally honest about it. But he's one of those guys that won't be fully totally open and honest, because he's too attached to saying what he thinks he ought to say to get what he wants.
Right now your boyfriend will be feeling a lot of "sunken cost fallacy". He'll feel that he's invested 12 months into you, and he'll keep investing till he gets what he wants.
If you were to meet the right man, there's a high chance you'd be having sex with him within 3 months of first dating him. Because everything would feel right and you'd be confident that you'd be doing the right thing on going on a sexual adventure with him.
I think you already instinctively know this: withholding or granting sex as a way to get a man to behave how you want is completely the wrong way to go about things.
If the man is right for you, go ahead and have a sexual relationship with him. If he isn't; have a sexual relationship with someone else (even if that someone else is yourself).
Never embark on a relationship with a man in the hope that he will change for the better.
Embark on the basis that he will change for the worse. With him appearing to be so good from the outset that even if changes somewhat for the worse, you'd still want to have him.
If there were a shortage of good (enough) men, it might make sense to stick with Mr Twenty Six.
But there isn't. There's an abundance of good to great to men. So there's no logical reason at all why you should stick with him.
And there's no logical reason why you should delay breaking up with him. The sooner you break-up the sooner you'll be free to get yourself the man you're destined to get.