Thanks for posting your query.
As you mentioned you were using Oxyelite pro
two months ago and now you are not having your periods despite negative pregnancy
Oxyelite pro contains large amount of caffeine which adversely effect your periods. It could be possible cause that you are not having your periods.
Take plenty of water and regularly exercise.
Kindly avoid Oxyelite pro during pregnancy and visit your doctor and get ultrasound
done to rule out pregnancy and other possible cause that may delay periods.
hope it helps.