Unity project

Please read entire project this is a simple task as I have most of it done. I have a game that starts with 3 weapons input of 1,2,and 3 and index of 0,1,and 2 now in the game the player can pick up more weapons so when they doit enables it allows them to use it. now the job is that I need to have it scroll through the active guns only as well as when the player uses the scroll then they can use the left mouse click to choose the gun and then it will change in the players hands and ready for use. Right now the script works as follows it will scroll up and down 0-8 and 8-0 without issue but since i have 3 weapons it should ony go from 0-2 and 2-0 until more is picked up. When a player picks up a weapon say its gun 5 then it should work like 0-4 and 4-0 not showing gaps and so on. I have attached the gunSelector script. IF anyone who is awarded the job feels they cant do it then they should backout so I can find someone else. ask me any and all questions and I will try to answer them to the best of my ability.