Does A Girl Have A Period Every Month Of Her Life Until Menopause?

I studied the menstrual cycle at school already… but I failed to understand some key concepts..
Does a woman have a period every month of her life until menopause? If she does, how come I’ve never seen my mom’s bed sheets with blood?
Now this other question is a serious question… when in porn movies, they sometimes don’t use protective gear like condoms. Doesn’t the female get pregnant when sperm is injected into her vagina?
What’s a tampon and how is it used?

Is It Safe To Be On Depo Until Menopause?

I’m 26 now and don’t plan to stop using Depo until menopause. I don’t want to get my tubes tied in the event I MIGHT want to have another baby though after losing my second to SIDS this is unlikely.
Anyway, do you think this is safe?

How Long Until My Period Is Regular, And When Does Menopause Happen?

I hate that my period’s irregular! I always think that I’m fine and then I go and bleed all over my underwear at school when I can’t just change them and wash them, and the blood sets in. I’ve had my period for just over a year, so I know that it can still be bouncing around, but for how long?
And around what age does menopause occur? On second thought, what is menopause exactly?