Hello . First of all I am 19 years old . I will be turning 20 in march . Normally I start my period around the same time every month . Its always on different days but its usually the last week of every month . In October I didn't start until the 31st and it carried over in November . I haven't started for November yet but the other day it looked like I may have spotted a little bit but didn't fully start . Is that normal ? And is that considered me missing my period for November or is when it carried over count for October and November ?

Don't think of your period as following the calendar months because a cycle can be anywhere from about 24-29 days. Check your start dates from the last year and calculate how many days you tend to have in your cycle, everyone is different. Use the numbers you calculated to determine if your cycle is still occurring when it should.

Keep in mind women who are together tend to ovulate at the same time and your period may shift to coincide with the periods of women you spend a lot of time with such as family, roommates or co-workers.
Ber