Ma'am I would suggest you to get a detailed Refractive error check up done. There are certain rules of refraction where a minus number people has to be under corrected and overcorrection has its own issues. The final correction given is always checked for Duochrome balance and if the need is there a dilated refraction is also done. If not using proper spectacles and not following a proper working pattern for your near work like laptop/mobiles then headache can occur frequently.

Generally, at your age a eye power is checked after putting some drops which relaxes your eye muscles. - 0.2 difference in power won't lead to headaches. Better to get a detailed power checked at a clinic near you.