Problems with starting, <<Whats wrong???>> Options

[Niskyspy]

Hello, well lets start from the begining.
This started happening to me in the begining of the summer.
1) First thing, the car didn't want to start from the first try.
2) Couple of week later it changed, when I try to start it all I hear is a click like the starter is engaged but cannot start the engine. But on the 2-3 time the engine would start anyway.
3) Now especially if it's humid or its raining the car will start from 6-20 tries and its the same thing, all I hear is a click and no enigne spinning and then after a couple of tries it starts normally.

What I did:
1) Brought it to AutoZone and checked my starter (my friend who works there told me that my starter is 100% fine).
2) I thought it might be something with electrical so I ordered and changed, (spark plugs, ignition coil, ignition rotor), the I cheked and cleaned battery terminals and added an additional 4ga ground. But nothing seemed to work.

I would like to know if any of you had this kind of problem with 6g and what you might this this starting problem is caused by.
Thank you very much