High weights, 6-8 reps, are used for building muscle mass. Lower weight and more reps (15 to 25) are used for endurance and fitness. What you are doing is someplace in between, but geared more towards the strength and muscle mass than the endurance.
Having been in both a female and a male body, I can tell you that it’s very hard for a woman to get definition, because fit women have about 25% bodyfat. This makes muscle definition virtually impossible. You don’t even begin to get definition until you drop to 15% BF and the good definition comes at under 10%.
If you want definition, it can be done, but you will probably need to drop at least 10 lbs of fat and maybe 15. It’s not easy for a woman to drop fat without losing muscle. You don’t say how much cycling and running you do.
To maintain my 8%BF, I cycle 25 to 50 miles per week and workout hard 3x per week, using a mix of lower weight high reps sets (up to 35 reps on some) and higher weight 12 rep sets. For ab definition, I do ab work every day, using the SynerAbs program: http://www.home-gym.com/synerabsii.html
BTW, what that consultant below says, “light weights with high reps is low intensity which does not cause a measurable increase in the resting metabolic rate after exercise nor does it deplete muscle glycogen stores”, is total BS. If high rep exercise didn’t delete glycogen stores, then why do marathon runners hit the wall at 20 miles? That what cardio is: it’s light weight high rep exercise, and it most certainly does deplete glycogen and elevate resting metabolic rate.