Welcome on HCM.
The varicose veins
do not appear due to masturbation
whatever amount you do it.
Leg veins have some one way valves and they allow pumping only one side that is towards heart.
These valves may be at fault in your case.
Second you work condition might be forcing you long standing in single position, so avoid this type of work. You can use legs elastic stockings to prevent the blood to stagnate in legs.
While lying keep your legs above heart label.
Do good exercise to tone up you leg muscle so that they can pump blood from legs to heart efficiently.
Get well soon