Period 6 days late. Negative pregnancy test hCG too low?

My period is 6 days late I took a ClearBlue test this afternoon and it was negative...

Is it possible that my hCG levels are still too low?

If I am pregnant I got pregnant around May 19th and it was during my fertile window a few days before I was about to ovulate. Since it is now a few weeks I feel like the hCG levels should be high enough to show up as a positive by now and I’m a little worried about ectopic pregnancy.

I went out of the country to a different time zone with a 9 hour time change so that’s how I know I got pregnant on or around the 19th If i am.

Could the jet lag be messing with my period? Also I was taking melatonin to help with the jet lag and I heard that this can mess with your cycle too.

I feel like I have been having some mild cramping and back pain and have been really tired but this could just be from traveling. I’ve also been nauseous at times but haven’t been throwing up at all.

I just want to find out ASAP so I know for sure that I have to avoid alcohol too much caffeine make sure I’m eating well and taking prenatal vitamins.

Has anyone had a similar experience with a negative test that a few days later came out positive?