The death of the old social life... does a new one rise to take its place?

There were lots of things I was told before I had the baby. One of those things was that my social life would be forever changed. That seemed obvious. They said we would spend more time with other couples who had babies - clearly that has not occurred. Before we got married, I was also told that getting married would result in more time spent with other married couples. This is simply not true.
But I realized something last night at 3am when I was tending to my crying baby. Greg and I aren't Friday nigh or Saturday night people anymore. We used to regularly socialize with friends on evenings during the weekend. Things don't get started until at least 7:30pm and go into the wee hours of the morning. But now - we put Rebecca to bed at 8:30pm, and we don't get to sleep in. Going to something that starts 7:30pm or later is just too late for us (on top of the fact that something it can take a good chunk of time to assemble Becca's gear for going somewhere). For special occasions, we are willing to disrupt her sleep, but hauling her over regularly to someone else's home where people will be noisy and animated when she needs to be settling down, just isn't good for her. It's a little different taking her to grandparents homes - because they understand when we duck out early. Then again, anything we do with them starts in the afternoon. You can't duck out early if you just got there - what would be the point? The alternative is one of us going off to socialize and leaving the other plus baby behind, but clearly, that isn't too appealing.
Our social life has been morphing before our eyes but we've been too tired and busy to notice. Because most of the members of our social circle do not have children, they still get to socialize in the late night way. We're the odd ones out. When you've been friends for people for decades, you don't worry about them disappearing from your life, but you do wonder what the new social life will look like. I suppose it's the way the cookie crumbles. You do wonder if others can really understand why you keep opting out of things (hopefully yes).
Of course, it is possible for us to socialize at night if people come to our house, but as we are in the midst of preparing to move, we don't have the greatest locale for entertaining. Besides, all our friends with huge brand spanking new houses and no anklebiters like to host things.
Having a young baby means every day is different. My life is all about flexibility and change. Making promises about the timing of stuff or being reliable is really challenging. Rebecca always comes first - it's the way it should be, but it doesn't mean I think other pursuits or people are second fiddle. My time is accounted for in more ways than when I did not have the baby and was working. When I have spare time, I feel the weight of opportunity cost more than ever before. My top choices is often sleep or spending time with Greg.