A negative home
pregnancy test using first-morning urine is usually reliable, especially this many days after intercourse. Your emergency pill can also shift your next period by several days or weeks. That fits with the irregular pattern you're describing.
Next Steps
If your period still hasn't come in a week, repeat the test and track your dates from here. Your irregular cycles are worth treating as their own concern, separate from this test.
Health Tips
See a gynaecologist if periods stay irregular over the next cycle or two, so the cause can be checked properly.