Hi I Had An Abortion In March After That In

Hi i had an abortion in march after that in may i used Norethisterone for 15 days to delay my periods when i stopped that i got my periods on 30th june for 5 days i took a pegnancy test on 28th june which had a very faint positive line i went to my doc she said she can not see anything in ultrasound
Can Norethisterone cause false positive pregnancy test??