While we don't have a recommended cultivar list for garlic as we do for some other vegetables, our Growing Garlic in a Home Garden web page does have cultivation information that might help improve the harvest in future years. Is the planting site still receiving full summer sun? (6-8 or more hours of direct light.) If not, that might be reducing the yield and vigor of the plants. Does the soil still drain well? Making sure the plants have the ideal site conditions is a good first step to troubleshooting the issue, since variety differences are probably not that pronounced (or else we'd likely have listed specific varieties to grow).

There is a new-ish insect pest in garlic, onion, and related plants called Allium Leafminer which can cause crop failures or widespread damage to mass plantings. It can infest crops during two windows of time over the course of a year, and preventing access to the crop is important by covering the plants just after installation with either floating row cover or insect mesh netting. The link above provides more information and other management options.

Miri