Thank you for including the 3 images with your questions as they help clarify the issues. Your boxwoods have been affected by 2 different insect pests.  The curled (cupped) leaves are affected by boxwood psyllids whereas the leaves with the small blisters and browning have been damaged by boxwood leafminers.

Boxwood psyllids (Psylla buxi) are tiny sucking pests that feed within the shelter of the cupped leaves.  These insect survive the winter as eggs underneath the leafbud scales.  As the buds open in spring (usually April) the larvae (youngsters) hatch and  begin to feed. Positive evidence of their presence are small white curled filaments near branch tips. Their damage is easier to tolerate than is the unsightly browning caused by leafminers. In most instances, naturally occurring beneficial insects such as ladybugs and lacewings limit damage. 

Boxwood leafminers (Monarthropalpus buxia) attack the new spring growth shortly after the new leaves unfurl. The adults begin to fly in early May.  (They may appear several weeks early this year.) These small flies resemble tiny, orange mosquitoes (about 1/8 inch long) and will swarm around the shrubs or cling to them. The adults die within several days, shortly after they insert eggs into the leaves. To minimize damage, prune the boxwoods before new growth begins and destroy the clippings. (These insects survive from one year to the next inside the blistered leaves.) Resistant varieties include 'Suffruticosa,' 'Pendula,' and 'Argenteo-variegata.'