Frazzaboo, that is your experience, but it is not universal. That is the thing about fertility, it's all so personal so all the anecdotes about oh well I did it easily at 41 are totally irrelevant when you are thinking about your own chances of conceiving.
I was never sure I wanted kids and was having far too much fun in my mid 30s to want to find Mr Right so just thought I'd leave it up to fate, by which I meant I thought I'd meet someone and do it the conventional way.
Then I found out I was pregnant unexpectedly after a 2 day fling with an ex in thailand at 36 and I now have 22 month DS. It is not an impossible task in the early days. It is hard, but motherhood is hard full stop. And I still maintain that it's easier on your own than with the wrong person.
I think the plan a PP said earlier is good - spend a few years enjoying life and actively trying to meet someone, then if you haven't, go for it. I have quite a few friends in this position now, and they all come and talk to me about it because of my situation and I always say, if I knew then what I knew now, I would have cracked on with single motherhood. I was lucky though in that there was no decision to make for me.
However, my best mate (38) is currently going through the pain of struggling to conceive. it's been 2 years and she just had a missed miscarriage after her first round of IVF worked. She could never have known she should probably have started trying to conceive 10 years ago, but it is heartbreaking all the same. Another friend (32) went to get checked out as she has had bad endemetriosis and turned out that was fine but there were other problems which means she has to start IVF right now then freeze embryos. If she had waited until 35, it would have been too late for her. I don't mean to scaremonger - as I said above, it's all so personal.
If I was you and knew I definitely wanted kids, and knowing what my friends have been through, I think I would go and get the full fertility tests done. At least then it's an educated decision.