What does it mean that I got insulted when a mammogram tech asked if I gained weight since last mammogram and then she hurt me?

Change on mammogram. The technologist may have asked because of a change in appearance of the breasts on the mammogram. Sometimes, adipose tissue is deposited in the breasts as one gains weight and the breasts look larger compared with the prior study.
It means that. You have thin skin about your weight, and hate the "compresion" associated with mammograms - -do you really think the tech was being cruel and sadistic? If you do, file a complaint at the center that did you mammo. But i'll bet you did gain weight and you are sensitive about it! ;-}.
Weight gain. Possibly your mammogram changed in appearance, or technical factors changed, and tech asked about weight gain to account for the change. Compression can be uncomfortable, but without it the mammogram would be useless. I doubt if the tech was purposely trying to hurt you, most likely she was trying to take the best picture possible. .