It doesn't take an expert to read someone's body language. It's just a matter of paying close attention. If the object of your affection is in love with you, the way she holds herself when she's around you should be a dead giveaway. When you're sitting next to each other does she cross her legs towards you? Is she always leaning forward when you're sitting opposite one another?
Some negative signs could be that she folds her arms across her chest a lot, crosses her legs away from you, or doesn't make eye contact very often. This doesn't necessarily mean she's not in love, but it definitely doesn't indicate that she's head over heels either. Try not to be discouraged, it might still just be early days. Some women need a bit more time to feel relaxed and comfortable around a new partner.