is it normal to not get your period after like...3 or 4 months? because im getting kinda freaked out....

What you're experiencing is secondary amenorrhea. That is when periods have occurred but have suddenly stopped.

There are many different possible causes for this. Since you're not sexually active, you can rule out pregnancy.
The most serious cause may be polycystic ovary syndrome. It's not as scary as it sounds. I think somewhere around 1 in 10 females have this. There are other symptoms that contribute to PCOS. Check them out link

Are you underweight or overweight? This can have an effect on the regularity of your cycle. I had primary amenorrhea (my period didn't start until I was 17) because I was very underweight.

If you have lupus or diebetes, that could be the reason.

Being under a lot of stress can also have that effect.

Are you sexually active? If so, you might need to get a pregnancy test and make sure you're not pregnant.

If not, then it might just be irregular. Mine has always been regular, but i know TONS of girls who may not get it for months and then get it. It doesn't mean your weird. However, if you are worried about it i would talk with your doctor or gyno just in case.

I thought it happens every month?

No its not normal! but mine do that too! ive went a year and 3-4 months wiht out a period once when i was 12!

no it is not normal,u should go to doctor