I'd say it's absolutely normal to be so scared - I had two losses, at 10 and 8 weeks (the second being a MMC which my body hung onto until an ERPC at 12 weeks). When I got pregnant this time, I didn't want to tell anyone (apart from OH!) and I was terrified history would repeat itself.
I had an 8 week scan and saw a heartbeat, but that reassurance wore off after a couple of days, and it wasn't till my 12 week scan I really believed it was happening (and I was bricking it then too, as I'd had pain for a few days and was convinced that was a bad sign - it wasn't). Even after that second good scan I started thinking something horrible might've happened and I wouldn't know... so at 15 weeks I got a cheapie doppler from Amazon, and now if I feel a bit paranoid I just listen to the hb.
But as for blaming yourself, aw honey please don't, from what I've been told the vast majority of early MCs are because of a problem with the baby, and certainly aren't anything to do with anything the mum does. So please lighten up on yourself here!
I'll be keeping my fingers crossed for a sticky bean for you...
*hugs* XXX