As a parent of both biological and adopted children, I can tell you that I went through a similar transformation that you went through with the biological kids, and then through a just as significant transformation with the adopted ones. (As a note, they were adopted right from the hospital.) What I was learning is that the "my" kids was not what any of them are*. They are not my possession, but someone I get to have an enormously close relationship ans responsibility to. This doesn't mean that there isn't a bond, quite the contrary, but that the bond is more realistic and better understood, just as you now understand what the bonds in your family friends ans S/O's through your children.
I know you had a question about surrogacy, and this is not exactly that. I will tell you that the bonding with the adopted kids did take extra time, but it is there, and it is just as deep as it is with the bio kids.
*Note: I am not trying putting words into your mouth, but this how I think I saw things with the first bio kid.