Overtime work loads in project

Question

Hi. I am working in company as Android developer since last 14 months. My question is on overtime work load in company. We had a project which has very tight dead lines. That project was also in iOS. So we had spent over night hours like reach company at 10:30 morning and come back home at late night 3, 4 or some times 5-6 AM. We were doing such works due to less experience for 2 monhts. Yes, we worked like this for continues two months for 14 to 16 hours with no saturday/sunday leaves. We couldn't oppose that we could not work much without pay. Because due to over load of work, it affects my health and body cycle was changed and late night food put me in trouble of weight problem. After completion of project, coz I haven't taken any leaves since last 9 monhts, when I applied for leaves, they refuse to give some of them. They just said me you are "unprofessional". When I told them that I worked so and you are not giving me leaves which are mines, they told that if you had problem in project, you should told to your project leader at that time that you could not work after 8:30 PM (which is over company leaving time). Added that you are only responsible for your health when I told them about my health probem (like eyes distance number, back pain, elbow etc). Its true that whole year this problem is not there. Like 8 monhts are good to pass with enjoying work and 4 months are heavy loaded which replaces 8 months work. Second is, they were not going to hire any other senior person right now due to salary problem. Another project is also coming which has also very tight dead line say 2 months and I am only one who has responsibility. They just answered, "we are going to hire someone to reduce your load" but till date no any fruitful result i see. Can you suggest me or make a glance that do I need to forget all things and do overtime works like 14 to 16 hours without extra pay or as professional (as per them I am unprofessional) I kindly say them to hire another person and will not work late night for 2 months.