No periods

The last day of my period was June 21 2020 so July and August came I still haven’t gotten my period and all my test is negative me and my fiancé have been having sex I tend to track them just because it’s interesting. What can be my issue? we are TTC but I don't know what’s happening I’m kinda nervous because back in March we lost our first baby and had a D&C done. Doing research i see that could cause an issue. We are TTC. The hearts are sex days and green checks are test days all came back negative