Getting a blood test...

After getting both positive and negative results on urine tests I'm having a blood test tomorrow. I'm 13 days late but I have Mirena since two months ago. My boyfriend never cums inside, I don't have any pregnancy symptoms and overall I feel very normal.

Would a blood test be enough? Like 100% accurate?

I'm really nervous, even tho the dr said I wouldn't get my periods I still tested out of curiosity.