Thanks for your query.
Spotting is more a symptom of pregnancy
than a sign of pregnancy.
the yeast infection in no way indicates a pregnancy.
As the pregnancy test is negative, you are mostly no pregnant.
however, as you said it was a cheap one so could have been faulty.
Please consult a doctor for the blood test
or better still, an ultrasound
sometimes, an ectopic pregnancy or a very early pregnancy might not be diagnosed on urine test.
All the best.