Okay In New To This, So Im Not Sure What Im Doing xD 

Okay So Im Gunna Start By Saying I Am Alsmost 18 And I Recently had unprotected sex with my boyfriend, However he did 'Pull out' before he went, I Do also realise this isn't 100% effective and i've always been very safe with sex so i realise how stupid i have been. But Im Unsure As To Whats Going On. My Boobs appear bigger, feel heavy and solid and are sensitive to touch.My Belly Hurts Quite A Bit At Night And My Tempreture gets Quite High And I Cant Sleep, I Always Sleep On My Front Due To 'Feeling Vunerable' But Now Its So Uncomfty.I've Gone From Never being hungry and barely eating to always being hungry and eating Loads. I Appear to have lost weight however the Scales say i havent moved.I've Alos Been Going To The Toilet More, But Not To Pee. Which Is Unusuall As Like My Mother Im Often Constipated.I Do Feel Ill Nor Have I Thrown Up, Only at night does my belly feel funny as well as severe heart burn.The Majour Issue is My Periods NEVER sorted themselves out, i can go 4 months without one and then i'll get one.. so i have no idea when im supposed to be due, or if i've missed it! I Know i have missed over a month since the last time..Im Freaking Out, And I Suppose All I Really Wanna Know If I Could Possibly Be Pregnant And Buy A Test To Find Out, Or Wait A Few Weeks To See If I Get My Period. Oh I Did Have The Spotting Twice.. Weeks Ago Thou.I've Taken A Test, It Came Up Negative, But Im Still Not Sure I Trust It. Its The First One I Have Ever Done And I Couldnt Do It From Due Period Date As I Have No Idea When That Is..My Belly Is Now starting to feel tight and uncomfortable... and i am so tired.Sorry for the Caps/No Caps.. Habit Im Trying To BreakPlease Help Me! Many Thanks <3