It's been a month since my period came. Took pregnancy test five times but have result is negative. Anyone have similar experience to share?

3 months ago, I went down to the polyclinic to get myself checked if I was pregnant, after not getting my period for 3 weeks. Results came back negative. The doctor then told me it could be just my hormones, stress, or lack of sleep. My period did come. After 59 days. Not sure what happened then! Now it seems to be regulating. The last few months have been 25, 26 and 28 day cycles.