Blood test worries

So a bit of a story.

I took a digital pregnancy test 14 dpo and got a positive. The next day I took one to confirm (line test) and it was negative. Now I am 18 dpo and still have not gotten another positive (last one I took was 2 days ago). My cycle is 28 days and I may start 1-2 days late (I accounted for this) but I am now 6 days late from my latest start time. I have been having frequent urination and sensitive breast and a TON of fatigue. I’ve also started getting car sick which was never a problem before. I’ve had some clear sticky/ jelly like discharge but very little of it.

My doctor is having me come in for a blood test. This will be our first so I’ve been freaking out and I’m unfortunately a researcher till there is nothing left to research. Has anyone else had a similar experience?