It may be OK for you to cut your calcium intake now but be careful as you can end up with oseroperosis. Your unlikely to really notice it until you hit your 40s when you will likely end up wheelchair bound after a minor knock to your spine breaks your back and as your bones are in such poor condition they do not repair, you end up disabled for life.
When you hit your late 20s your body starts to decay, bones which had been building up until then stop growing, stop building. Its from then your body is depending on a healthy foundation (ie what you have been feeding it all the previous years) by the time its gotten to 40 your going to begin the menopause within the next 10-15 years, your bones will have begun already to decay. The more calcium you can put into them before you hit 30 the less likely you are to have brittle bones when you hit 40.
If you have brittle bones (osteoperosis) its not good. Once your bones break, it can take a very long time to heal, not like when a kid or someone in their 20s breaks a leg and it takes a few months, it takes much longer, and even iron plates. Its painful, uncomfortable and will prevent you from being able to exercise properly. You will be at risk of being overweight as a result or if weight is still an issue to you then, not eating very much at all.
Trust me its the last thing you want.
I have seen/known many people who have osteoperosis, its not in any way good. Its so simple to add in some milk every day- just add it to waht you already eat eg breakfast have milk with cereal or porridge, or after a workout have a plain yogurt and fruit (milk is actually very good for your body after a workout). Although green veg has calcium in it the quality is not the same and it takes much much more of it to get the same effects.
Please really try to eat healthy foods- your eating 1600kcals of what if you can't include calcium in it? I used to eat 1060kcals a day (I was anorexic at the time) even the I was able to get in some milk everyday! Its not impossible and is a good thing to include.