Mine are nearly 8 and 5, same gender, and we have decided to stick with two. It has been a very hard decision to make and has taken me about 18mths. My OH was much clearer. He has always been happy with two but was willing to try for a third if I really wanted it and thought I would regret it if we didn't. No one has a crystal ball though. We can only decide in the moment. I think for me, finally realising that whatever decision we make may not be without regret helped me actually make a decision.
I'm 42 and while I would not be trying naturally for a 3rd at my age (I know plenty do but not for me and especially not for a 3rd) but we had fertility treatment for our two kids and have some frozen embryos remaining which are much 'younger' than any I conceived now would be. In some ways they feel like ready made kids in waiting that we have a duty to use. But they may not work and we wouldn't ever get to use all 3 embryos anyway.
And a pregnancy at 42 has risks for the mother and baby even if an embryo frozen years ago if being used. We are comfortably off and could afford more children. But I feel a 3rd would take away too much from my two kids and would put unreasonable stress on my husband and I and our sanity. I love my kids dearly and had a tough journey to have them but neither were decent sleepers until away into the pre school years and now, while they often are the best of friends, I find the noise and squabbling that also happens very hard to deal with at times.
Also the fact that my husband and I are not both 100% about a 3rd makes it a no for me. An accidental pregnancy would be a different scenario but that's not what our situation is.
I have had miscarriages in top of fertility issues and one difficult labour and birth. The risks of another pregnancy just scare me too much and no longer feel viable. And the risk, however small of myself or any third baby suffering harm, or of us having a multiple birth, is just something I can't get past.
There are so many threads on MN on this issue as I discovered when doing my own research last year. I didn't even need to start a new one. There seems to be quite an even split unlike the poll results here on this thread when I last checked. People always say you only regret the kids you don't have but I'm not sure I agree and find that a bit trite and removed from reality.
For me, it's a hard pill to swallow. I love the idea of 3 or 4 kids and especially a larger family in my old age but that's not where my family building journey has led me and my parenting bandwidth is much better set at 2 kids than anymore.
I feel sad to be out of the baby and toddler phase as it has so many highs and happy memories for me despite the sleep deprivation. I also feel sad not to have the experience of having children of both genders. But I'm trying to look forward at all the good things to come and to count my blessings, which is another trite offering often quoted in this situation.
Good luck deciding OP.