Did I test too early? I tested on the 20 and 21. Which is cd 18 - 19.

Implantation occurs 6-12dpo with 9dpo being the most common day. You tested before implantation could even take place. You’re only 7dpo today if you truly ovulated on the 17th.I would wait until at least 10/11dpo before testing.

If you're pregnant you probably haven't even implanted yet, so the test is going to be negative now even if it will become positive next week. Wait until the day your period is due.