Delayed Period After Clomid: Causes & What to Expect

Question
I am 29 years old.  I have two children.  My last menstrual period was on Dec. 3, 2004.  I have had two normal cycles each lasting 21 days.  This month it is different.  I have been taking Clomid the past two months also.  Now this month I am on Day 27 and still have not started my menstrual cycle.  I have taken a home pregnancy test and it showed negative.  My question is--Will Clomid have caused me to go longer this month?  I don't even feel like I am going to start my period.  I am also worried that I may be having an incomplete pregnancy due to me not having a positive pregnancy test.  I have been trying since April 2004 to have another baby. I began using the Clearplan easy fertility monitor in July due to my inability to get pregnant.  I was ovulating in July and August but then in September I didn't ovulate at all according to the monitor.  I just don't know what is going on and what all Clomid can do to my body.  My ob/gyn suggested clomid to help get me ovulating.  Please tell me everything you can about Clomid and my situation.  Thanks for all your help!

Answer
Clomid increases your chances of ovulating by causing a negative feedback in the hypothalamus, which increases production of FSH and, therefore, more follicles will mature, increasing your chances of ovulating. Usually you should take the Clomid on cycle day #5,6,7,8, and 9 and you will ovulate around cycle day #14. If you do ovulate on cycle day #14, and become pregnant, a pregnancy test will not show a positive result until 14-21 days later. Your cycle should be 28 days (from the first day of your period until the first day of your next period). I would continue using the Clomid for 6 months, and see if you do, indeed, ovulate and conceive. Do not give up hope or get frustrated.