Thank you for your query, i understand your concern and i am happy to be of help. Considering your age the calcium requirement is 1000 mg if you are a male and 1200 mg if you are a female.
Too less or too much of calcium have their side effects, too much of calcium can cause kidney stones
, abdominal pain
and other such problems.
It is good that you are already taking calcium in your daily diet, try and include in your diet, foods rich in calcium like milk, yogurt, cheese, fish, broccoli, cabbage,and citrus fruit juices.
Your age being above 50 there is requirement for calcium supplementation other than what you take in your diet. I would suggest you to consider taking calcium carbonate
tablets ( 1 tablet will provide you with 200-400 mg of calcium). Even calcium lactate as you mentioned were taking is a good supplement option.
Get you serum calcium levels checked and get back to me with the results, then i would be able to help you with your supplement dosage.
As of now the diet of calcium rich food and a tablet of calcium supplement a day should be good.
wish you good health.