Research shows that most women ovulate 2 eggs 10% of the time. Your instances of ovulating more than one egg would depend on if fraternal twins run in your family or not. If you do ovulate twice, it will be within days of each other. Obviously your normal cycle is just longer than normal. You probably are only ovulating once in this time.
If you just started taking birth control your periods are going to be irregular for the first few months. But it is possible to still get pregnant on the pill.
Yes, this can be totally normal. In order to menstruate regularly you have to ovulate regularly, at 11 years old it's unlikely that your body is mature enough to ovulate on a regular basis so irregular periods or lack of periods is normal - even when you're a little older, as your body changes this can effect hormones and your cycles by large so result in irregular periods. If concerned then talk to your doctor if you've gone over three months without a period.
I have been suffering lower back pain on the left side and Irregular periods
If you have irregular periods, you can still get pregnant. Unfortunately the only way to tell if you were ovulating (other the over-the-counter tests) is by having a period 14 days later...by then it is too late. So you can skip your period for 3 months strait, then ovulate and get pregnant without warning, and then you won't get your period because you are pregnant and not know for many months.
Everybody is different but that happened to me for the first 8 months :)
See your Doctor as you may have irregular periods.
If you have recently started your periods, or are in the first year or so since it started then your periods may be irregular or late. They should fall into step.
Most start at 6 months of age and then every 6 months. but if a dog is irregular you may want to keep an eye on her because you wont know. but most dogs have it 2 a year but it's possible she may have it 4 times a year when she's irregular.
You can't really say because everybody is different. But it's usually the first 6 months that will be the most irregular.
That'd be a bit unusual, but not impossible. Periods are often irregular in the beginning, and stress in particular can upset the schedule.
It can take months for your periods get back to normal, especially if you are breast feeding you can miss periods or have long times between them. You can still get pregnant while breast feeding and having irregular periods though so you should still use contraception.
After you stop the birth control pill, your cycles will return to their natural pattern within a couple of months. If your periods were irregular before you went on the pill, they're likely to be irregular after.