Period 3 days late..

Hi everyone so in April I got my period on the first and in May on the fifth I was supposed to get it a few days ago I'm on the 38th day of my cycle with usually 35 day cycles. I've had migraines every day and cramps but my period isn't coming. I took a test the day before it was supposed to come and also like two days ago and they are negative. Could I be pregnant? Also I am not on birth control and did have sex almost every day this month.