Yes it is. Hormone problems can make you skip. Sometimes getting use to birth control pills can make periods longer or shorter between or make the period not come .
Yes if this is the way your period has always been then it is normal. Also if you are on birth control then you will be more likely to skip a period. But there is also the fact that you could have an issue with fibroids that is causing your period to skip.
There are a lot of variables that can affect the menstrual cycle. Stress, birth control, age, just to name a few. Make an appointment with your gynecologist to be safe.
No. It's not really normal to skip your period. A number of things can actually alter your monthly period. Things like stresses, major changes such as moving or a new job or an illness can change your period.