Pregnant?

I would like to know your thoughts and if anyone has been through what I am dealing with.....I got a positive pregnancy test but since then have bled alot. Because of this, my doctor has ordered blood work. I have had it done 4 times now, increasing every time but only by about 450. I have had 2 ultrasounds done but have been told nothing is there even though my numbers continue to rise.

I am having more blood work done Monday. Thoughts???