Im 19 and this is my first pregnancy and i cant help worry. I had pregnancy symptoms for weeks (missed period for dnt know how long, really tender breasts, backache, nausea, constantly hungry etc) before i took 2 different makes of pregnancy tests 3 weeks ago and they both came up positive, one of them said i was 3 weeks plus. so after that i booked a app with the midwife and got asked the same routine questions, she asked when my last period was but i dnt know cause my periods have never been regular and because i wasnt tryin for a baby i didnt think twice about not having missed periods. she wrote on her book that i was about 10 weeks, that was just a rough guess though. i had to wait 2 weeks for a appointment for my scan and its today , im really excited. thing is all my symptoms went away about a week ago. i suffered mild cramping in my abdomen and stomach about 2/3 week ago, phoned the midwife and she said its nothing to worry about. i cant help worry now becuase i dnt have any of the symptoms i was experiencing for a good few weeks. sorry for the long post, need some advice 
