Hey all,
Numberjacker 
I'm really sorry hun, that's shit for you. Please take heart though that it will happen. But I do know how crap it is. When I desperately wanted a baby (not long after having DD), I used to get upset when AF arrived, even if we hadn't SWId at all that month - now that was just weird!! 
You are welcome to finish all the caffeine, alcohol and chocolate. I will replenish the stocks. Big (((((hugs))))) for you. 
Fluffy, I second what the other ladies have said but also, just to let you know... My Dsis is currently PG and is about 17 weeks now. She is a size 24 (pre-preg size) and her BMI was around 35 (again pre-preg). So I really don't think that you need to worrry. Having a healthy diet etc helps and all the 'giving up caffeine' and stuff. But all you have to do is look at people in Africa and even people in the Western World who take drugs/smoke/drink too much, they all manage to get PG, normally without trying. You can look at all the statistics in the world and look at what we're supposed to do, but it doesn't mean that it won't happen for you anyway. Always keep that thought in the back of your mind...
Child, I was out with my friend last night who was asking the same questions as you, we had a nice long chat!! So, Day 1 of your AF (Bleeding, not just spotting or cramping) is classed as CD1. In a perfect world, our cycles are 28 days and again in a perfect world, CD14 would be the day that you OV. Therefore the week leading up to that day are the best times for SWIing. CD15 to CD28 are called the Luteal phase, which for most people is 14 days. The longer the Luteal phase the better as it gives more time for the egg to get comfy before AF would be due. Those with a shorter Luteal phase tend to find it slightly more difficult to keep a PG going in the first few days because the egg doesn't always implant sufficiently.
The only way to really find out when you're OVing is to follow a couple of things. The first is to take your BASL temperature (pref first thing in the morning before getting out of bed and after at least three hours sleep), every day for a whole cycle. You will see a pattern of steady temps and then a drop right after OVing. If you're PG the temp won't drop and will start to go up instead. Secondly, by checking out your CM which should be Egg White for a few days before OVing.
There's loads of stuff on MN about it, I found it amazing that I knew so little when I started TTCing DD! So, lesson over, hopefully you will find some of that useful hun.
Clandy, I know what you mean about going to work hun. I had to go back to work when DD was only 4 months old. It was a new job aswell and I hated it and it led to me being signed off with depression. I really thought I wanted to be a SAHM and that that was the main issue. But now I'm in a job that I enjoy, I realise that actually being a SAHM Mum wouldn't be for me. I worship DD but I do find that I get bored quite easily with 'toddler' games. Whereas I am very happy in the knowledge that I'm paying someone else to keep my gorgeous DD occupied AT ALL TIMES. If she was here with me I'd be doing housework or watching the TV. She has a much better time where she is! 
MPT, how are you doing hun? Absolutely get those wellies on and get outside. We've only just managed to buy DD some because her feet are so dinky (she is a tiny 2 year old) that she's not even in a size 4 yet. So we bought some size 4s thinking that within the next couple of months, she'll be able to wear them - fingers crossed...
Hope everyone else is Ok!
Passing around the biscuits and crisps. But I have to have some toast first. Catch you all later.