Positive test and some opinions from you guys..

Ok so on oct 9 i test and found out im pregnant now this test came from the clinic since my friends work there and came home with them to test me..so i told my husband and hes in disbelieved we have a 4 and half years old girl and we havent use no protection ever since so he dont believed it he thought he couldnt have no more babies ..he say he wont get illusions till he goes to the doctor and confirmed it..what u girls think about this? Can u guys help me calculate how many weeks i am since my appointment is next week. So at the end of august i saw brown spotting for 3 or 4 days i didnt recall it as light period because i was using panty liners ..so september period never came and now we here oct 13..how long you guys think i am? My last major period that was so horrible was july..