I know I've been asking a lot of questions about fasting, but this has been an area of concern for me. I know you're supposed to start fasting at the age of puberty, which for girls is the age when they started getting their periods. Anyways, I didn't start fasting at that age because I didn't know we were supposed to. I can't remember but I was either 12 or 13 when I started fasting. My question is how can I make up for that? I've heard that once the next Ramadan starts you can't make up the fasts for the previous Ramadan which means I definitely can't make up the fasts from 6 Ramadan's ago. Is it sufficient for me to do voluntary fasting for every day that I missed? And is it okay if I don't do it right away because I'm very skinny, like 84 pounds and I'm 16 years old. My doctor says I have to gain weight and my parents would never let me fast right now in this condition, unless it's for Ramadan. If I tell them my situation, they would say I'm going crazy and that it doesn't matter, but I'm sure it matters. Fasting and prayer are a big deal in Islam.