Hi Wiggles
I have had a similar experience to you: easy first conception, healthy DS but secondary infertility, although for me it was due to scarring I suffered after giving birth.
Here's what helped me to decide what to do:
I asked the consultant his views - he gave me the usual stats (20% success rate, how your changes lower the older you are - I was 37 at the time, the risks involved etc). None of that sounded good. I was also scared about pumping a load of hormones into my body, and whether it would make me crazy.
Another thing that influenced me was thinking about, what if I successfully conceived and yet there was something wrong with the baby. I know this could happen with any pregnancy, but I think I'd feel more responsible with a pregnancy that I had 'made' happen, if that makes sense (I know you 'make' any pregnancy happen, but this felt different to me).
Not sure if you've thought about this, but I was also uncomfortable with the idea that if the lab managed to create several embryos and I didn't use them all trying to conceive, that they would still exist and eventually have to be destroyed. That felt funny to me (even though I am not an anti-abortionist or anything, and don't believe the embryo is a human being or anything, so I'm not sure why I felt that way).
These reasons are mainly medical, but the other thing I thought about was more philosophical. I kind of wanted to be able to count my blessings. I had been lucky enough to have a child, healthy and happy, with no problems. A lot of people didn't have that. And the consultant had said something to me that really hit home - I asked what he would do in my position, and he said that he felt that he had a much stronger responsibility for the children he already had than to one who didn't exist.
SO....
I decided not to go ahead with IVF. However, it wasn't a straightforward process. I did doubt myself a lot, especially when I came across people like londonlottie who did have firstly, the courage and determination to go ahead with it, and secondly, the good fortune for it to have been successful. londonlottie, I am so pleased for you that it worked out, and you're right, it isn't too bad for a lot of people, which is great. I don't know how to reconcile this with the sadder stories where it hasn't worked out. It's impossible to know which one I would have experienced. Maybe it comes down to whether you are a risk taker or not, and in this arena it felt more... what's the word?... authentic/honest/realistic (not sure i can articulate this properly)? to see the decision as already made by 'nature'.
The decision did consume a lot of my thoughts for probably two years. Like you, a lot of friends were having their second or third babies, and it was difficult. I felt broody and I felt sad, but it has got easier. I did a good job on myself of focusing on the pluses of having an only child, of which there are many, and now i actually quite often feel relieved that I only have one when i realise how much work having more is (My DS is now nearly 8, so I am a few years on). I know it's not perfect, but then is any family perfect??? We are still a family, and we have a good time together, so i am happy with my decision on the whole. The question of what might have been now feels like any other 'what might have been' question, like what if I'd taken that job instead of this, what if I'd chosen to go to a different university and so on: it's a hypothetical alternative life I could have led, but didn't choose.
Just to finish, I should say that my DH was initially quite keen to give IVF a go (let's try it once and if it doesn't work we can leave it) but he supported me decision, and was also able to be philosophical about it. He also said he didn't feel really strongly either way, so that really helped as i wasn't fighting someone else's opinions.
Sorry this is such an epic post, but I hope it helps. I also hope I don't sound smug in any way. I think whatever you decide there will be times when you wonder if it was right, but good luck with the process, and try not to let it consume you - you still have a life to lead right now, and one you can enjoy whatever the outcome of your fertility issues are.