The boy I like sends himself a text message after drinking, saying that he has been drinking.

Whether you think too much or not, first of all, he didn't text his girlfriend after drinking too much, but sent it to you. I can see that he is a bit of that (I don't know because he is a boy you like). If he is drunk, he probably doesn't take it seriously, and he may be really a little lost. Some boys just like ambiguity, so you are still wise.