i have the same problem. i have always been really hardcore with my cardio workouts and havent been able to gain much muscle specially in my arms whic is what i want. i have recently tried to find answers for this too..the only good info i have gotten so far is to not do cardio on days you do leg workouts bc you wont gain the muscle. i also think the reason i havent been able to gain any muscle is from what i read on a women's health site saying that if you do serious periods of cardio workout then you can start to burn your muscle as well specially if you are slimmly built. so you might want to ease up on the cardio and then do at least 3 times a week of strength.

you need to do less reps and heavier weight to get bigger... and yes tone down the cardio. protien is good for building the muscle you want. but remember to be grateful for the slim body you have and just try and make it healthy for what God has given you!
try kickboxing to give you a good cardio workout, and still build muscle...its so much fun!

I agree - less reps (I reckon about 12) with heavier weights and I'd only do cardio on the days you don't do weights.

Spirit 13. It is hard to suggest a routine for you since I don't know alot about you. I would do as the other suggest do reps between 8 and 12 with heavier weight. As for the protien shakes it depends on how much protien is in your diet. Remember to much protien turns to fat. If you take your body weight and multiply by .4,.6 or .8 will give you the amount of protien you needs. Like for me I am 180 and if I use .6 I need 108 grams of protien a day which is 432 calories from protien.

As for cardio you don't need to go over an hour unless you are training for a marathon or something. After that you use up your glycogen storage and start burning protien.

It is a tough thing to build muscle and keep it. Just keep working hard eating good, and stick with it. Also don't worry about getting to big women aren't built for that at least not naturally. Hope this helped at least a little.

if you want non-glute shakes, try the syntrax brand. you mix with water, easy to drink a multitude of flavors and 23g of protein in each one.
if you have a slim build and want to build muscle you must do higher amounts of weight with less reptitions. I would recommend laying off the cardio and hit weights only for say, 1-2 months. you then build the type one muscles whcich give you the strength and look of bigger muscles, however, cardio, running, etc. strengthen the lean type two fiber muscles which make you look more lean/cut. I find that if I want to build I do the heavy lifting for say, three-four weeks, then get back to running/cardio to lean up. been fairly effective for me with maintaining strength and building a leaner body. still have the rough edges on teh mid section that older age is getting me, and can't keep away from a cold one or two on weekends...

Please consult a personal trainer. I did this and it made a world of difference, but the core of it is all what you put in your mouth, in conjunction with a specific workout schedule that is designed specifically for you. And get enough sleep - that has been scientically proven to increase the muscle building hormones in our bodies.

Do more weights, less cardio. Can you have licorice root? It may help with that. Its known to increase size but does not seem to have the nasty side effects of a steriod. Good luck. I stay away from it because of my PCOS. I make muscle without even trying. Have your hormones/testosterone checked out. Make sure that everything is in order there.