Thoughts please?

I took a HGC test on Monday which shown a second faint line, however I took one the day after and it was a BFN.

AF is due on Friday and I am now 12 DPO.

On Monday I had such bad nausea which was the main reason I took a test. The next day my nausea disappeared completely.

Has anyone else had this?

My excitement is now non existent as I am worried I may of had a chemical pregnancy