We bought 13 hpt's from the dollar store. I've been testing every day since 11/13, just for fun. Because I had an IUD for the last 5 years, I had no AF. However, I do have other cycle symptoms that make me about 90% sure that I O'd on 11/11. I'm thinking the earliest I could possibly see a 2nd line would be 7dpo? What are your opinions/experiences with this?