You can definitely ovulate without having a period before. A period is usually an indication that you recently ovulated -- not that you WILL ovulate. The period is caused by an unfertilized egg and uterine lining leaving your body. This time the egg was fertilized (yay!), so that's why you haven't had a period. The problem with having irregular periods is that you never know when you will ovulate.
I guess the doctor that said you are about 12 weeks is able to tell based on the development of you and the baby. They usually know what they are doing. When cycles are irregular and ovulation dates are unknown, sometimes the doctors continue to adjust the EDD as they monitor the progress of you and the baby. But it will probably be around the 18th of April.
thx sweetie. i understand now much better :)
ok so i just spoke to my doc she seems to think its ok and that i can come and see her a week before the date she had asked me to come now (she asked me to come and see her on nov 9, week 14, so now i m gonna meet her nov 2 instead (13 week, 4mnth) yay, to that!!! she seems to think aisa koi urgency nahi hia tests ki but she said theek hia come 1 week before the date i give u and then she will have blood, urine and diabetes checked. i did tell her that my other pals on GS has had that done in their first trimester but she said 1 week, 2 week se koi fark nahi padta.. silly woman .. i m gettin all worried here :D thnks again for everythin sahar