Could it be period or am I pregnant?

I got my IUD birth control out on March 19 and my partner and I have been having sex almost every day since. I had one period cycle and now am 4 days late. Yesterday I had just little blood and thought I started a period, but no blood rest of day or today. Two days ago I took a test and it was negative. However, last few days my boobs have been sore and I've been told that I'm very emotional and asked numerous times if I am pregnant. How much longer should I wait to take another test?