Real sex is soooo different...and at the same time, so similar. It's unlike anything you imagined it to be, and at the same time it's kind of like whoa, not that big of a deal after all.
Of course from thereon you will want it even more than you did before, but that's okay.
On the lasting issue, that's not something to worry about. It'll work itself out, and even if you are the fastest gun in the west, it will change in time with experience and stuff.