D.M.
I have 3 boys and love it.
I had my first son when I was 39. We brought home son #2 (adopted) when I was...oh..44 or 45 (I am losing count:). My husband and I had always said we wanted 3 but I had just had a lovely week with our oldest and my husband had just carried a screaming scared baby on a 17 hour flight. SO we agreed to stop at two at that point.
AND...within the week, I realized I was pregnant. Son 3 definitely completes our family. I can't explain it but...it just is. Other than the first few months, I haven't found 3 to be all that much harder than 2 (though 2 is a LOT harder than 1). The hardest part is that sometimes one is crying and has to wait while someone else's more immediate need is being met. While, as a parent, that is tough, I don't think it's a bad thing for kid's learn that, even if they are hurting, they don't always have priority.
My oldest was 4 when his first little brother came home and 5 when the next was born. He had a hard time for about a year and a half...but now he can't really remember life without them (he's 6 and a half now). He's a proud brother.
I say do what feels right for you. Many people will comment on finances...and college...and so forth. I put myself through college and it's not the worst thing in the world. The main thing is that your kids are fed, warm, clothed, and loved. If they have that, they can handle the rest if they have to.