S.,
First off my heart aches for your loss!! I"m so sorry you've had to endure that pain. All that said don't give in to those feelings yet darling. It is a lonely dark place to be, I've been there. And this is totally cliche, but when I finally let go of it I was pregnant a few months later. Very VERY cliche. You'll hear people tell you to let go and let God until you think you're going insane, and that "as soon as you do...." But I know it doesn't feel that way, it didn't even feel that way when I did let go.
Now, back to the pregnancy test stuff. ;) I'd give it another week, then test again. But you don't want to drive yourself nutty buying them and having a lot of negatives. Check in with your ob/gyn soon to have a good checkup. IF there is something 'wrong' he/she is the place to start the discovery.
On a side thought, every pregnancy is a miracle. Every positive test is a miracle. To think of all that goes into just getting that positive is amazing. What you've had was a blessing and a miracle and yes it hurt, it still hurts. A lot goes into it all to make just one happen. :)
Hugs. I wish I could make it all better!
V.