i agree and disagree with ip man/wehrmacht on this. it's not healthy to be 'obsessed' with a girl yet i don't think you're obsessed at all. i just think you really like/love her and most people pine for their significant others when they are apart. it is normal. the problem is knowing if you two are really going to sustain a happy, fulfilled relationship once you both take the next step in life. if you know that you are going in different directions and will find it hard to maintain the relationship because of time or distance constraints, you should end the relationship on a good note and keep talking as friends. time heals everything, and soon you will feel better about it as long as you make a promise to yourself that you aren't going to keep on with a relationship you know you or her can't dedicate yourselves to because of things going on in your lives.
conversely, if you know that you have a good chance of sticking together, you need to ask yourself if this is what you want. i don't know how old you are, but it makes me think that you might be young considering your problem with your parents. if you are, then you just need to sit down and tell them that you are serious about this girl and that she makes you happy. if they try to brush you off and tell you that you are young and naive, tell them that their talking down to you about it isn't going to help because it's just going to make you unhappy. you are young and you are experiencing a relationship, much like they did. remind them of this. also remind them that (i assume) the girl isn't getting you into any trouble at all, so you don't see what the problem is as you're both happy together. if they have concerns that you are spending too much time together, dedicate more time with your family, which will help you cope with not spending as much time with her - which is ideally what you need to do. there comes a point, even when two people are infatuated/in love, that you need to cool things down a bit. other wise it gets intense and you start not being able to handle more than a day away from each other. if your family is flat out stopping you from seeing her, providing your relationship is good, then screw them. go and see her and be back in a timely manner or whatever so they can't bitch at you.
it's a fine line to tread, and considering that i don't know all the details of your predicament i can't just give you one solid piece of advice. hope this helps.