Hoping for the best

Catrina • 25. Married to my other half. 5-15-15. 1 angel baby named River. Daughter named Remington. Son named Journey.
Does anyone know if an infection could have returned a false positive for trisomy 18 or 13?? 
I had a tooth taken out a week before I got the first trimester screening and was taking an antibiotic and then I got a result of 1:12 for trisomy 13  or 18. Could there be anything that caused a false positive? I took the harmony test today to get a better answer 
Baby looks perfectly healthy. Nothing psychically wrong at all. Here is my last scan at 11 weeks and 3 days. I find out the gender tomorrow at 15 weeks 
Second picture is baby from the screening but it's not as good of quality.