Emergency pills can delay a period, but that effect wears off well within a month, so the May pill isn't why August is late. A cycle up to around 37 days is still considered normal.
Next Steps
If your period still hasn't come by around mid-August, take a home
pregnancy test and see a gynaecologist for a proper check.
Health Tips
Don't take any medicine to induce your period without your doctor confirming it's needed first.