The negative beta-hCG means pregnancy isn't behind this 3-month delay. A gap that long usually points to a hormonal cause such as
thyroid,
prolactin or PCOS rather than anything urgent. The blisters below the lips with a high HSV IgG and borderline IgM most likely mean a common cold sore, separate from the period issue.
Next Steps
Get
thyroid,
prolactin and a pelvic ultrasound done and see a gynaecologist to find the reason for the delay. For the lip blisters, keep the area clean and dry and let them heal on their own over a week or two.
Health Tips
See a doctor sooner if the blisters keep recurring or spreading, or if periods still don't return once the cause is treated.