You are not using the right words - you should think of yourself as petite rather than short (unless you are short but very fat, but with a small butt I doubt that you are). Does "petite" make it better?

Many men like and cherish petite women. I think you should leave the guy and wait for somebody who will not tell you that you are not his type. Plus, not kissing...

I would recommend that you leave him, slowly rebuild self-esteem, and then, with luck, a better man will appear on your horizon. You are too young to be trying all of those things to attract him back. You have no children together - what are you fighting for? If I were in a situation that a man I am with cannot get it up without watching porn together (I have never been in such a situation so I am writing about it as a hypothetical), I would promptly exit the ship, unless there were some OVERWHELMING reasons to try and work it out. I just do not see any sort of an overwhelming reason in your post, nor do you appear to love the guy, which, again, speaks for separation, as far as I can see.

The earlier you exit, the earlier you will start regaining your self-confidence, and that, as noted above, will be projected and help attract better male specimens.