You may be a 'normal' weight for your height, but what is your body composition? Chances are, you're also around a 'normal', average body composition, which is ~25.1% bodyfat for a female.
Regardless of you feeling "bulky", you are actually NOT. I am just under 5'2", and at 118lb (which I easily get to on and after my extremely high calorie/carbohydrate days), I am still SMALL, even if I don't feel like it.
You canNOT do exercises to "flatten your stomach". And there is no such thing as "toning".
"Toning" is either:
a. Losing bodyfat;
b. Gaining muscle mass; or
c. Losing bodyfat and gaining muscle mass simultaneously (i.e. recomping).
To "flatten your stomach" and "tone your arms and legs", you really need to look at your nutrition, since it sounds like you want to lose bodyfat. As far as exercise goes, make sure you're training effectively and efficiently for your goals.
The article
The 3 Keys to Fat Loss explains nutrition and exercise for effective fat loss. I highly recommend that you read it, and start applying - if you do not already - the principles in it.
~Team APPNUT