I know I've said it before, but here it is AGAIN: It's hard to build muscle.
Any woman you see who is lean, muscular and defined has put in a LOT of work to look that way. She didn't get there by training with light weights, not eating enough OR by just doing tons of cardio. It took EFFORT day in and day out to get that muscle.
You don't wake up one day and with bulging biceps and popping shoulders. You will NOT get massive or bulky and look like a man, despite what people(especially MEN!) may say.
So if you want to be toned, my advice to you is to try to build as much muscle as possible. Make that your focus in the gym. You do that by lifting heavier weights(of course with good form!), for 6-8 reps, focusing on your biggest muscle groups and exercises that don't just isolate one muscle. Pullups, rows, bench presses, shoulder presses, squats, and deadlifts are some of the best exercises you can do for building muscle. And stick to mostly barbells and dumbbells-I'm no longer a fan of machines!
You also have to be sure to eat enough HEALTHY foods to fuel those muscles and get them to GROW. Get in more protein, eat your healthy carbs before and after workouts, and don't forget about the healthy fats, like olive oil and avacado. Eggs, fish, lean meat, fruits, veggies, nuts, oats, brown rice, and whey protein should be staples in your diet.
And lastly...don't overdo it on the cardio! Focus on the weights, clean eating, and throw in a little cardio in there a few days a week. Do some sprints or jump rope intervals on your days off from the weights, or right after your weight training sessions. And don't forget your rest days-your muscles grow outside of the gym on your recovery days, NOT in the gym.