HCG levels 3 weeks pregnant??

I was curious if anybody has ever had their hcg levels tested at 3 weeks pregnant? After having intercourse almost every day/ every other day for the last 2 weeks, I decided to test for the heck of it. I got a few tests that had EXTREMELY faint, questionable positives. Some also were negative..I’ve also had some random tingles in my breast like last time I’m as pregnant and spontaneous light cramping in my uterus. I decided to go and get blood work done. My levels was 6.4.. I was told an average no pregnant woman has 0-5 HCG & positive pregnancy is above 20. They want to have me come back to test again in a few days because 6.4 is in the grey area. I could either be super early pregnant or for some reason carrying more hcg in me?? Anybody ever have super low levels like this and turn out to be pregnant???