All little boys are destructive, wilful, cruel, one-dimensional little bullies.
Do you feel cross with me? Are you seething on behalf of your wonderful boys? Good. Such gender stereotypes are utter crap. Gender tells you nothing about a child other than a biological fact. It doesn't tell you if they're shy or confident, sensitive, gregarious, tall, short, witty, inquisitive, loving, caring, demonstrative etc etc. All children are unique and wonderful and anybody who can so pigeon hole them has missed out on all the joy of creating a truly unique little person. How simple their world view must be.
There's an interesting psychology around having a 3rd. I read something about it years ago and see it on here often. There's an odd mix of fear that it will go wrong and benign indifference. From what I recall it's partly to do with a subconscious belief that you're pushing your luck (please excuse the terminology, I'm not explaining this well). Perhaps a belief that one child worked out well, family unit all good, second child, gosh aren't we a happy family it's all good, third child oh cripes what if this one goes wrong, what if it was one too far. There's the mix of knowing you have more to affect (2 children and a dh and an established family) and also the psychological shift of going from more adults in the house to more children. It's a real leap of faith. And unbalanced too. Sharing things between two, simple, between three, oh it's a different mathematical equation.
What I'm saying, albeit clunkily, is that there are good reasons why you feel the way you do. I think the lack of emotion is more a defence against some of the subconscious fears.
And really you do know the reality. PFB was brilliant. Second born you were more confident and had the joy of introducing siblings, 3rd born, well same old same old.
It comes as quite a shock sometimes I think how much you adore your 3rd after thinking you're so passive about it for months. And sometimes easier because you're quite laissez faire about the whole thing.
You'll be fine.