I agree with your username. Try not to be too harsh on yourself. Let the doctors do their checks and you might find there's nothing to worry about at all. You know you're not alone with your fears, you know you won't be alone if your fears come true. You might read back over this post in a month time and laugh at how scared you were when it ended up being nothing. It's good of you to recognise why your boyfriend might not be taking it so seriously, I'm guessing it's a bit of a "boy cried wolf" situation, but that doesn't make it any less scary for you. If you've diagnosed yourself plenty before and been wrong then, how is now any different? Really. What about now is different to the other times you've scared yourself?
I posted probably an hour ago that every time I've been convinced there's something wrong with me, I've been wrong. Every time - wrong. Now when I'm "convinced" there's something wrong with me, I think back to every other time I was wrong. Every time I thought I was dying, yet I'm still here. Every time I thought I was sure to get bad news, yet I didn't. Every time I thought I wouldn't last, but I have. I still get scared but those memories help take the edge off a bit. Are you in the same boat as me? Have you scared yourself plenty before and been wrong about it?
You're most probably not dying. You're most understandably scared. You're most certainly not alone. x