If you had an unprotected intercourse
3 times then there can be chances of early pregnancy
You had abortion
almost 3 months back and it is very unlikely to have a positive test.
It can be a false negative test also
Get it repeated after 15 days and blood tests for HCG levels.
You can take progesterone
as advised by your doctor , there is no harm in taking it if you don't want to continue pregnancy