Thank you so much jeanjeannie, pwcbird, didoreth and tnp. It's really great to get so much reassurance so quickly.
Tnp I don't live in the UK so I don't see a midwife, just my consultant. Next appointment isn't until the 20 week scan and I don't know if my local gp equivalent has a doppler - I'll check tomorrow. A little bit of me thinks I shouldn't give in to myself because, as my husband says, the worry won't be over now from now on, EVER! And I really don't want to be a neurotic mother. The other bit of me is saying ANYTHING for peace of mind.
I did have some bleeding from the placenta at the beginning of the pregnancy but the baby was growing fine and it had healed by 13 weeks. The thing I don't understand about the cervical erosion is why, if it's not the placenta, I have to rest. The doctor I saw last week when I was admitted as an emergency, says it's to do with the psychological effect on me every time i bleed, but I'm not sure how great the psychology of doing nothing except worrying about the baby is. Of course I'm doing what I'm told but it would be great to understand!
Anyway, thanks again, you've all really helped.
It's nearly bed time (well, for pregnant women) in my part of the world, so I'm off to eat something sugary as per advice, but now won't worry if the butterflies don't come!