From your description of the weight loads you currntly use, I suspect you have an imbalance of upper body strength. You use a moderate weight for chest work, but very light weights for biceps, triceps and shoulders. You don't mention what you use for back work, but it sounds like your chest is worked much more and is therefore stronger than your other upper body muscles.
You should know that continuing to increase your work load with weights will not bulk you up. You say you do not wish to "grow your muscles" any further, but as muscles get stronger they get more compact, so you won't be adding much size at all, just greater strength.
I think it would be a good idea for you to incease your weight loads and continually strive to build your overall bodily strength. Here's why: you don't say how old you are, but by lifting weights and building greater strength as you age you protect yourself from the dimunition of muscle tissue that affects all women from the mid to late thirties onwards. Decreased muscle tissue means your metabolism slows down, you burn less calories and the ratio of fat to muscle in the body increases in favour of the former. Not good.
Also, to continually work on improving your strength helps you build and maintain bone mass, which will also decrease as you age. These are naturally occurring processes, but the bottom line is that weight lifting, and lifting to your maximum ability at that, helps slow down the aging process and the effects of this in the body.
Not only this but greater strength in your muscles can help protect ligaments and joints from future injury. A good strong back will help your posture and a strong core will help you in all your daily and fitness activities. Think how many people lose work days due to aching backs. Train your back and make sure you don't become one of them.
If I were you, I would open up those GS DVDs and start working with them on a regular basis. Challenge yourself and get as strong as you can. Remember: weight lifting involves more than just aesthetics. It provides incredible HEALTH benefits.
Clare