Girls liftng weights, how can I get defined toned arms?

I want to get nice define arms. I always go to the gym, I do cardio lots of it run, elliptical, swimming, HITT, stuff like that, I have lost weight and look smaller. But I never can get my arms defined, like I want them to look like I lift weights! I look in the mirror and it looks like I never lifted any weights before. I do the machines in the gym for the arms all of them, 3 times a week ..3 sets of 12-15 at 30 or 40 pounds. I used to do them at 20 but now I don't feel anything. I do free weights sometimes but sometimes way too many people in that room annoying. SO what else should I do? ( I started to swim too just b.c. of my arms.). I do need to lose some fat, so should I keep doing what I am doing and keep the a lot of cardio is it just the fat that needs to melt? what's the deal