Same story here, friends getting pregnant all round and I'm the only one of us who all got married around the same time who hasn't had any children yet... it really does make you feel like some cursed person, doesn't it? I keep wondering, why us??
Background is I came off the pill in April '09 and we half-heartedly TTC-ed for a while but no charting or anything. I only started worrying about a year ago as my periods went totally haywire and I started getting 55 day and 43 day cycles, possibly not even ovulating at all, so went to the GP and was finally referred to the fertility clinic in May '10 but then a month later, I got my BFP and was over the moon about that. Then in August, I had an MMC just a few days before my 12 week scan and that was honestly the most horrendous experience I've ever had. It almost put me off TTC ever again 
But here I am, back on mumsnet, back cycle-watching, hoping I might be luckier this time...
It is so hard when it seems easy for others. As someone said further up in the thread, though, you do have to tell yourself that you never know what problems people have behind the scenes. I've never told anyone about my MMC, for example, so if I got pregnant tomorrow and it went well, nobody would ever know what we went through last August. That's the way it is with pregnancy, people talk endlessly about the good side and the good news but no-one likes to talk about the dark side - which just fuels the paranoia of us TTC-ers! I'm trying to stay optimistic and look ahead to maybe a diagnosis and some help of some sort in the New Year when I see the fertility clinic again. It's not where I thought I would be a year ago but I've learnt a lot in the meantime. Mumsnet has been so great in finding support and knowing that I'm not the only one so let's drink to that [clinks glasses]