You are going to need to do something ...
You must have valid photo id - if you don't drive, you can get an age of majority card. You r OHIP is questionable. For some inane reason the beaurocrats at Health Canada have disallowed its use for identification purposes (despite the fact that it is photo, contains your address, and your signature)
But, it sounds like you aught to get a passport. I still don't have one, having never gone anywhere it is required (a birth certificate is fine for US, Mexico, Dominican Republic, Bahamas, commonwealth countries) - but it is going to increasingly become important as a travel document. It is a much simpler document and is understood properly -- last time I went to Mexico the official actually stamped my birth certificate - invalidating it (I had to buy a new one when I returned home, which could have been a problem had I not met with understanding and not overly controlling immigrations officers on my return)
Have a great time in Vegas. I'm jealous.