It sounds like there was little risk of pregnancy. If you want to be totally sure, you can take and trust the results of a test 21 days later. No need to buy a $20 test—you can get them at the dollar store or online for a few dollars. You may want to buy a pack so you can test monthly and keep your mind at ease. Something like this is a good option (and is what they use at a doctor’s office). AccuMed Pregnancy Test Strips, 25-Count Individually Wrapped Pregnancy Strips, Early Home Detection Pregnancy Test Kit, Clear HCG Test Results, Over 99% Accurate https://www.amazon.com/dp/B071YNWRPP/ref=cm_sw_r_cp_api_fab_mnmIFbKB4SV8F