OPK struggle

Kayle

Can anyone help me understand opk testing??? It's my first month ttc and I'm only using tracking apps and opks. I started testing about a week after my last day of AF and haven't had any distinct 2nd lines. The picture shows my fmu (top) and another (bottom) at 3pm. My fiancé and I thought I was starting to ovulate but I took another at 10pm and the 2nd line was pretty much gone :((( we bd anyway and have been almost every night. I'm scared to death that I won't ovulate and was sooo excited to see a darker line this afternoon. But where did it go? Would there still be two lines if sperm met egg immediately?? What time of day is best to test? Can exercise or stress effect the test? Please help me make sense of OPKs!! 🙏🏻🙏🏻