You can request a BT to check the levels of HCG in your body now, or you could have a scan at 6-7 weeks to see how far along you are.

With our son, all the hpt that I did were very very dark and he was a single bub. This time around I did a couple and they were so faint that I thought there was no pg, it turned out that I am expecting twins. I don't think that you can ever be really sure with those hpt. Seems to be a bit af variation between them.