How many penalty strokes will I get?

Being a new golfer I had a half set as my first set. Those clubs where not treated nicely so I had some of them in my bag as "rescue" clubs. Clubs I would use in the woods or with lies where I could damage my new clubs.

Thing is, I counted these a month ago, and realized I had 15. I took one out the bag and thought I had 14. Played the tournament Wednesday and I never thought of the idea that I had to many clubs in my bag. Obliviously I must have added more of my older clubs without knowing it, because when I looked in the bag yesterday there where 16, and not 14.

Ironically this was my first stableford tournament wich I won but I have let the club know what happened so I'm going to get a penalty. I read somewhere that you can in one round get a maximum of 4 points (not strokes, due the stableford) penalty on the rule of too many clubs, is this correct?

Man it sucks to call a penalty on yourself when you won, and even though I didn't use any of those rescue clubs part from one of em, I feel the need to tell them.