Not sure what to do any advice

So I haven't had a period yet this month my estimated time for my period was the 18th I normally have my period towards the end of the month or the beginning of the next month. They are pretty consistent last month I had one start on new years and the another start on the 26th of January. I was suppose to have another start on the 18th of February but I haven't had one at all for the month of February. I have been sore and tired and have been feeling nauseous but its normal for me to feel that way before I start my period as well. But again I haven't had a period I'm kinda scared to test to see but also dont know If I should wait longer before I do just in case it's my period starts out of no where.