I took a HPT and it had a very faint line within 3-5 mins but after 10 the line faded away. I had no HPT left so out of curiosity I took an OPK and it wasn't positive but was a lot darker than usual and close to positive. I am 9-10 DPO today and I know you shouldn't use OPKs for HPT but I've heard this worked for some and I wanted to try it out. Anyone have experience with this and had it happen?