Heraclitus - Have you checked your credit score? that is probably the easiest way to know the impact of your activities. You can get a free trial and score at myfico.com. Most of the FAKOs were so off that I stopped checking.

Your post does not indicate if you are allowing your cards to close with a balance and then paying it off in full or if you are paying most of your charges before statement close. I am a Midwest bumpkin who had score in 820s, but now runs around 790-813. I paid to monitor the crap out of the score for an entire year to double check what I read/learned against my own experience. (BTW 84 Fiero and MDTR Chicago have oodles of very insightful posts that you can "stalk" by clicking their names and then all posts for a nice read). If you have 6 CCs all closing with balances of $100 it will negatively more than if you have one card closing with a balance of $1k. By monitoring closing dates and paying off to zero the majority of the cards, I.e. all but 1-2, you can quickly improve your score.

OP- I had two cards cause a 20 pt. drop when I first started as well. With a long history, it recovers rapidly. if you are obsessive, then pay to monitor and read up.