I had some bleeding with my first pregnancy up until 13wks and everything turned out fine.
I would wait and see what your BT show also you DR should have done a second BT about 3 days later to see if your hcg levels are rising so you know for sure what is happening.
It would have been to early to see anything on the scan and also your dates might be out just a little.
Will he be sending you for another scan in the New Year ?

I know it's hard not to worry and we all worry when these things happen.

I have had negative HPT's from the Dr's before in fact all my pregnancies have been confirmed by a BT.