Cramping?! Or miscarriage.

So I'm 20 days late for my period and I haven't taken a test because I'm kinda worried about the outcome. This has happened before where I was almost a month late and then my period came so I'm not sure if this is period related or not. I'm having sharp pains on my left side right above my vagina. Earlier I was having sharp pain in my vagina, along with some lower back pain. Could these just be period cramps or could I be getting ready to have a miscarriage?! I hope it's not a miscarriage because I'll be devastated!