Subchorionic bleeds are relatively common. They have no significance at all, except that you can bleed throughout your pregnancy. We had one woman in our practice, who bled enough for her hemoglobin to drop significantly. It went on throughout her whole pregnancy. We sent her to an OB who said, basically, ya she will bleed, and there is nothing you can do about it, and it means nothing. She had a lovely homebirth.
We have also had women who have had them resolve. They want an ultrasound for bleeding, and we order one, and then at the 18-20 week ultrasound, there is nothing.
So this is really just a normal thing...but very annoying. So, enjoy your pregnancy and try not to worry too much about this...but don't go lifting 50 lb bags of potatoes!!!