Is it wrong to call off work?

I am a waitress from Florida and I have been employed at a restaurant in the area for the last 3 years. I have never called off and I have turned into the “Go to” girl for everyone when they need off. I have an event upcoming in a couple of months and it just so happens to fall on a day that everyone else has requested off leaving me as one of the only waitresses that is able to work.  I really don’t want to miss this event as its my mothers wedding and it means a lot to me to be able to be there. I am worried that If I call off they’ll use it against me. I am not qualified for many positions so this job is very important to me. I don’t want to be a bad employee but I don’t want to miss this wedding..Is it wrong for me to call of work in my position? I have tried talking it over with the managment with no luck..I am stuck. Do you think that I am in the wrong if I call off work? Is it wrong??