Katniss and Marshmallow - please do not give up hope, not all bleeding is a bad sign. I had implantation bleeding when I got pg, but because we'd been ttc for 2 years I shrugged it off as the start of af and went to bed with lots of painkillers (kicked myself afterwards).
I got exactly the same symptoms as PMT - sore boobs, cramps, twinges, over emotional etc. so it is very difficult to differentiate. Also I was a couple of months away from starting IUI (before they try IVF) when it hapenned.
For me I think a lot of it was down to timing, there were bad things going on with me while ttc such as stressful job, being made redundant, acute illness, severe weight loss, then I got another (less stressful) job and some helpful treatment for my illness and I seemed to turn a corner.
So a month into a new job I found out a was pg, but I didn't even care as I was so happy. Unfortunately I wasn't kept on when they announced redundancies after 5 months (surprise surprise), but again I feel it worked out for the best as by that point I had developed PSD and had to use crutches and was very uncomfortable sitting at a desk, so although it wasn't great financially I had lots of time to rest and look after myself.
Now we are back ttc again and I'm having the same problems as before, but am trying not to get worked up about it as I just remind myself how lucky I am to have one child and to treasure every moment I have with him and not waste his childhood worrying about another one who may never come along.
You can't help getting your hopes up each time and I guess its that hope that keeps us going.x