Is It Time For Baby #3?

I've always said I would stop popping out babies after having 2. But I also always said my older boy would be an only child...and he's been living that older brother life for three years now. My ovaries think I just talk for the sake of talking. But baby fever is in full force and since I'm not getting any younger I should consider options, pros, and cons.

First of all, I'm 33. So starting all over, even if I got pregnant this second, I'd be 51 by the time the maybe baby turns 18. I'm not entirely sure if I have the mental or physical stamina for that. I'm exhausted by my self sufficient children. On the other hand I can totally make my older children help me with the new one (plus Dad obviously helps).

In terms of physical fitness and vanity, am I ready to have my body wrecked again to grow a little human? After my first baby I bounced back and then some into incredible shape. I'm three years postpartum with the second, and my body is taking a weird forever time to get back into comfortable shape. After a third, what will my body be like?

Also, is it selfish of me to bring a kid into this world? Pandemic, poverty, overpopulation, discrimination, global warming. All the things! Raising a kid in this world will present them with many obstacles. Tons to think about. And I'm open to opinions, suggestions, and concerns.