im 19 coming on 20 in like 10 days and think i could be pregnant, i haven't missed a period but my menstral cycle is unpredictable, i had unprotected sex on the 25/06 and have been feeling really nauseous, having dizzy spells, have pain in my lower back, and pressure on my lower abdomen and suffering with gass and trapped wind which i think could be causing the pain in my lower back (which is very unusual for me) i have to pass urine an awfull lot more than i usually do and have found that over the last week or so i have been so much more tired than normal. is this possible