If you want to lose weight, having muscle will help you, your body needs more calories to maintain and use muscle so you want to have muscle unless you like not eating anything.
You need good protein to maintain and buld muscle so yes, you do need protein, you will find it very hard to build and maintain muscle without it.
Your a women right? just to add please don't worry about "bulking up", you have only a certain amount of the hormones required to build up heavy amounts of muscle in your system and unless your eating and drinking vast amounts of growth hormones in your food, your not going to be able to become a body builder- all body builders have to dramatically alter their food or add in heaps of protein stuffs and other hormonal things to get the bodies they have, you cannot be the one person in the world to buck th trend and not need to take all those pills and forumlaes so please don't worry!
The going rate is 1 to 1.5grams of protein per kilo of body weight every day. A tuna steak weighing about 150 grams will have in about 30 grams of protein, you have to do the math to work out what is good and bad if you only have a limited amount of calories to eat with.
Some forms of protein are poor quality, try not to look on the back of a packer of say pasta and think "oh I can use that for my protein intake", its not good quality it is protein but wont help you much, try to stick to dairy, meat, soya... stuff that is protein rich and will help you more. Don't waste your calories on inferior protein hoping it will help!