I'm one of those people that knew before even having kids that I only wanted 2. Not to say that if something happened now, that I wouldn't "want" that baby, but I was totally content with 2. So I had my girl, then my boy. Both great pregnancies with healthy babies - and I was done. I did wait until DS was 2, and then I had the tubal ligation. I've never looked back once. I have a lot of friends with babies...and I sooooo enjoy them!
Also, when I had my tubal, my GYN mentioned that if I wanted to have another baby, I could (of course, I don't know the process) have one implanted and then I wouldn't need the reversal. She said insurance might not cover some of it...and that I should go into the tubal 100% sure I don't want any more children. Which I did. Just mentioning that, since she had mentioned it to me.
ETA - I was 30 when I had my tubal.