I did an FET and started at 5dp. My story was pretty similiar to yours. That first line was so super light and was after the "alotted" time. I think you have yourself a BFP!!! My advice to you is to keep using the same FRER or new FRER whatever you are using EVERY time. Don't switch brands or anything b/c that will drive you crazy. I was getting a faint line on FRER then swtiched to a different brand the next day and got nothing & I was devastated...for no reason. So stick with the same kind everytime you POAS! Best of luck!!! Can't wait to hear about your beta & U/Ss!!