I was depressed after I had my daughter. Keep in mind it is time-limited, and be sure you have a lot of help and support. You will need it. Having two is a LOT different than having one.
And yes, boys are easier, and unless you completely blow it, they love their mamas. More than girls. I would take 10 boys before I took another girl.
But if you are seriously questioning your ability to raise this baby properly, you should consider adopting him out. It's not too late, and your daughter is too young to know any different.