HI I HAVE TAKEN A PREGNACY TEST AT HOME YESTERDAY

HI I HAVE TAKEN A PREGNACY TEST AT HOME YESTERDAY IT WAS POSITIVE SO I WENT TO THE DOCTOR TODAY HAD AN ULTRASOUND NO FETUS WAS FOUND UNLESS I WAS TOO EARLY TO BE DETECTED BUT THE URINE TEST WAS NEGATIVE. SO AFTER THE VISIT I WENT AND BOUGHT 2 MORE PREGNACY TEST AND BOTH OF THEM ARE POSITIVE. IM CONFUSED SO I WENT ONLINE AND FOUND OUT THAT HYDROXYZINE MAY CAUSE A FALSE POSITIVE RESULT, THE LAST TIME I TOOK THE DRUG WAS ABOUT 5 DAYS AGO. WHY DID I GET 3 POSITIVE RELUTS AT HOME AND AT THE CLINIC A NEGATIVE WITH NOTHING SHOWING ON THE ULTRASOUND UNLESS IM TOO EARLY?? PLEASE HELP..