Period question!!!!plz help?

uhh,, does a girl have to have spotting before she gets her first period???!!! because im pretty sure i got almost all the signs for almost getting my period(my first)....im 12 and i have 32A boobs and i have some pubic hairs... ive been moody, tired, and having aches.. like in my back and ive been having some pretty strong cramps sometimes... like theyre REALLY REALLY strong.. once i had them so strong i couldnt even move.. i was in class that day and we had to go and put our stuff away... my grandma and my mom keep saying if i have been putting pads in my backpack because im thinking theyre getting the idea that im going to get my period any day now... but is it true the more you think about getting your first the more it keeps you first period from coming???? my grades have been getting lower since last month... i havent had any spotting.. but do i have to have spotting before getting it??? ive had dark discharge too.... like its almost yellow... does it mean that it might get dark enough to brown???? im getting confused and worried that ill never start my first period.. im in 6th grade and almost all the girl there have gotten their periods!! my best friend got hers last week!! my legs have been hurting too... ive been having discharge for about 2 years now..... growing boobs since i was 10... ive basically been through puberty since i was 10.... all i need left is a period!!! ive been getting headaches too.. like about 3-5 times every week! i need help! ive been having the cramps since december too.. but ive been getting them more frequently...oh yeah and my discharge is sometimes smelly.. like almost a metal smelling its strong and sometimes im afraid people at my school can smell it.... sometimes its not smelly.. plz oh plz just help me and tell me if im right about the signs .... and when i might get it... and my discharge has been stringy and like slimey.. ewwww