Moving on is completely normal.

Leisa would not have wanted you to sit at home alone constantly worrying etc.

Brett, you could honestly sit around all day and worry about whether or not things are "right" or "acceptable", but only you know how you feel. Everyone knows how much you loved Leisa, and I don't think anyone has the right to tell you that you can't be happy again, especially since even Leisa would not want you to dwell on this forever.

Do what you feel is right and in the end what will make you happy, because when it comes down to it, Leisa would most likely rather see you smile and be happy, than unhappy in any situation....