what have you hcg levels been like since teh 11, 16 and 31?
I'm sorry but it sounds like an early loss, some doctors call is a chemical pregnancy, i hate that phrase though.
The should give you hcg tests till the level is back to zero. They need to do this to rule out an ectopic. In an ectopic the pregnnacy will grow, but will never be viable and the hcg will not double every 48hours as seen in a normal pregnancy.
If numbers are going up still you need to be scanned.
Keep us updated. I've been though this and it is horrific. PM me if you wish.