My eyelids are single but there are double eyelid curve and lines above my eyes. When I try to widen my eyes the double eyelid eyes will appear.

It's fine. I am sure it is fine. Lots of changes and concerns as you go thru puberty. If it does not interfere with vision, don't worry too much. If it does, mention it to your doc next time you see him /her. Live healthy and be well!