Your boyfriend is being SO SELFISH it's not even funny!
If you are pregnant DEFINITELY tell him and if his determination to go to Texas with his brother is still the only thing on his mind then he obviously doesn't care about your feelings because pregnancy changes EVERYTHING in a relationship or so one would think.
Also if you are pregnant how is he going to support you while he's in Texas? He can't it doesn't matter what he promises you because of the distance. I don't like the idea did you know that you could easily move with him and finish out your last year down in Texas? YES you can do this it's not hard at all because you just need to register to the location where your boyfriend intends to reside. You would have to become an emancipated minor so that you are your own legal guardian. If this is not the case then it is up to your boyfriend to take care of you while you finish out your last year in Texas. I can't believe that he never considered this angle in his "BIG" plan to get on "HIS" feet. Like I said before he didn't even include you other than to "WAIT". What happens if he never comes back to get you? Sadly you would be SOL especially if you are pregnant to his child.
In this case if you are pregnant and he shows not morality to caring and says anything demeaning, hurtful, and says anything similar to "It's a good thing I'm moving to Texas then huh?" or "I don't care I'm still moving to Texas" or "How can I move to Texas now thanks this is all your fault" then you need to dump him ASAP even if he comes close to sounding like ANY of those examples.
If he is so focused to move you can't stop him, just like you can't stop him from finding someone new while he's down there for the next school year. Also if you are pregnant and he still moves THREATEN that you will pursue child support on his behalf. You have to keep in mind that the economy is really bad and it's not your parents responsibility to help you out, though if you can get it that would be awesome! But if he doesn't want to be physically there then his wallet will be and I STRONGLY URGE you to pursue child support if he is so willing to ditch you IF AND ONLY IF you are pregnant.
Mainly hold your breath, say a lot of prayers, and hope for the best. Try to stay as optimistic as possible for your sanity. Also make sure that you test yourself to see if you truly are pregnant because this is an urgent matter that needs to be resolved ASAP, and make sure you tell your boyfriend that you are sure that you are pregnant. In complete honesty you have to tell him that you are sure that you are pregnant since it's his right to know.
I wish you the best as you will need it!