Coming to accept the tattoo(s) you have is one of the best lessons I've learned from getting tattooed. There's so much trust involved in being tattooed, because no matter how much research you've done on artist, how many portfolios you've looked at, how excruciatingly you studied the stencil before having it put on your skin, when it comes down to it, you're basically trusting a complete stranger to permanently alter your body and appearance. As someone who generally likes to be in control of everything, getting tattooed allows me to practice letting go, being present in the moment, and accepting things I can't change in a way that few other things in my life can.
I only have three tattoos, but I have one that I had a harder time accepting than the others because the lines aren't as bold, the colors not as saturated, and stylistically is just a bit off from the bolder style I've learned that I prefer. I don't regret the tattoo, and I certainly don't hate the tattoo, but the point is, even if I did, it's there now! Nothing I can really do to change it so it's not worth worrying over.
I think your tattoo looks lovely and well done. I agree that it would be prudent to hold off on completing the sleeve until you feel more certain that's what you want. I think it looks fine as a stand alone piece.