in your case if pregnancy test has been negative even till date then you are surely not pregnant. the delay and irregularity need to be evaluated and investigated to rule out pcos (polycystic ovarian disease) hypothyroidism or hyperprolactinemia which are the most common reasons for oligomenorrhea in young women. for further information consult an obstetrician and gynaecologist online --> <link>
pregnancy test shows negative shall i take medicine to induce periods?