Because you have trouble putting on muscle, I don't think that you need to worry about getting too muscular for your taste. The other thing is that it's a very gradual process to put on muscle. So if you did realize you didn't like the direction your body was going toward, you could stop it before it got very far.
One thing for everyone to realize when weight training is that your muscles may swell while they're repairing after a workout. It's temporary and it means your body's working correctly. Some people freak out because they think they're going to get "bulky" because it's that "OMG! One workout made my biceps this big, what will happen if I keep it up?" feeling. But it is temporary and will go down.
ETA a link to this awesome video
of a very petite woman doing overhead body weight squats - check out her body if you're afraid of getting too big. What she's doing is very heavy and hard lifting.