So I've Had My Mirena For A Little Over 3

So I've had my mirena for a little over 3 years, I had a period the first month after and it disappeared after that until about 6 months ago when I started classes again and synced with all the other ladies. I've been sleeping with this guy for a little over a month and I realized I'm a little over a week late I've taken a test but it came back negative. Was it maybe to early to test?