So confused; my Aunt flo is playing mind games!?

I have a question; Last month my period came about 12 days late but before it came I took a HPT test just to be sure. It was negative & my period came. Great right? WRONG! This month I thought "maybe my period was a tab wacky last month, it will definitely come on time this month & it DIDN'T. So far it has been 20 days late which in my opinion is LONG, I just don't want to take a pregnancy test because I keep thinking Aunt flo would show her face but it haven't. ( The reason why I haven't tested by the way is because I have been late before and I do want to waste time nor money if its for nothing) Can I get some input ladies it would be greatly appreciated. Have this ever happened to you and you did end up pregnant? What should I do?