I know exactly where you are at. After a couple of m/c's i don't allow myself to get excited or be happy about a BFP. I guess it is a bit of a defense mechanism, if you're not excited you wont be as dissapointed. Probably a rediculose mind game we play with ourselves, but i think it is totally normal. I'd like to think so anyway!
I became a serial tester after my m/c's and for this preg i had a BFN and then two days later had a strong BFP. So fingers crossed this little one is here to stay. Best of luck.