When should I be allowed to feel this child is mine?

I'm still not sure I'm ready to talk about the failed adoption we endured four years ago, but something I read a couple of days ago got me thinking about the whole event again (not that I ever stop thinking about it, but it made me want to express a thought).  To condense a long, painful story into a few sentences, we were in the process of adopting a baby boy in 2007, and due to a number of lies the birthmother told, the supposedly "unknown" father found out about his son, and got him back after five months.  We were devastated, to say the least.  And even though we are thrilled with our son, now, and even though we knew the birth father was not at fault and had every right to have his son, it was the most painful experience I've ever endured.  We cried every day for months, and that's not an exaggeration--not all day, but at some point every day, I broke down.  I read a post on an adoption-related site on Facebook a couple of days ago that referred to adoptive parents as sometimes feeling "entitled" to a child that isn't officially theirs yet, and there was some discussion in comments following about how it's such a difficult decision for the birth parents and that we need to respect their right to take some time to make that decision.  And although I completely agree that it must be an extremely difficult decision, I have to say that I think it is unfair to think that adoptive parents should just care for a baby until the birthparents make up their minds as to what they want to do.  It think it's unfair to the adoptive parents and also to the child.  I hold no animosity towards our first son's mother.  And I have absolute compassion for our current son's birthmother (who actually passed away from a drug overdose before we even finalized our adoption).  But I think there are sides to consider all around.  In California, where we are, I believe the system weighs too heavily in favor of reunification, to the point where many children are dragged through the process for years until they reach an age where they are much less likely of being adopted.  I know of a girl who has been in foster care her entire fourteen years of life and is now struggling to be placed in a family, desperate to have parents and somewhere to call home.  During the first twelve month's of D's process, there were still chances for his birthmother to change her mind and fight to get him back.  It would have been difficult but not impossible.  Such painful decisions all around.  I think after a child has been with you for twelve months and the birth mother has made little or no effort to get him back, that perhaps you should be able to feel a little entitlement.  And I don't mean that in an arrogant way.  I have love for everyone involved, but at some point, enough is enough.  When is that point??