A
beta hCG under 0.1 along with three negative home tests makes pregnancy essentially ruled out at this point. The i-pill you took is a common cause of delayed periods, since it disrupts ovulation and can push your cycle off by two to three weeks. The light spotting on 20 and 21 September was likely breakthrough bleeding from the pill rather than your actual period.
Next Steps
Give it another week or two to settle, since cycles often take time to normalise after emergency contraception. If your period still hasn't come by then, see a gynaecologist for an ultrasound and hormone check.
Health Tips
See a gynaecologist sooner if you develop pelvic pain, heavy bleeding or fever, or if your period hasn't returned within three weeks.