I am 19 years old and have recently gotten off "the pill" (which I had
been on since I was 15 to solve an acne problem and irregularity)
because my doctor said that it was causing my
reoccurring yeast infections  The date is June 2 and I haven't had a
period since the beginning of March.  I am worried that something is
wrong.  Last week I took a pregnancy test and it came out negative. 
My boyfriend and I have been very careful and use condoms each time we
have intercourse.  What else could be wrong?  Help!

The technical term for what you're experiencing is known as secondary
amenorrhea, which is just a fancy way of describing the symptom of not
having menstruation but having menstruated before.  If you search for
that term on Google, you'll find out more than you ever want to know.

Google search term: "secondary amenorrhea"
://www.google.com/search?hl=es&ie=UTF-8&oe=utf-8&q=%22secondary+amenorrhea%22&btnG=B%C3%BAsqueda+en+Google

Actually, technically that doesn't describe you, because the term
usually isn't used until menstruation has been absent for six months.
The most likely cause is the change in hormones after coming off the
pill, and that isn't unusual at all.  But if you or your doctor are in
the least concerned that that isn't the reason, you should get a
thorough check up to make sure.  And if it lasts longer than another
few months, you should get a thorough checkup even if you aren't
worried.

Note the following:

Secondary Amenorrhea
"Following discontinuation of oral contraception some women will not
have periods for up to several months. However, the reported incidence
for amenorrhea lasting more than 6 months after the pill is stopped is
0.8% which is essentially the same as the incidence of amenorrhea in
the general population. Therefore, amenorrhea of greater than 6 months
duration after oral contraceptive use is not related to the pill use."
http://www.advancedfertility.com/amenor.htm

I looked at various sites, and here are some of the causes, in no
particular order:

hormone imbalance
excessive stress
extensive exercise (it is common among hard-core athletes)
anorexia nervosa, bulimia or other types of malnutrition
problems with the adrenal, pituitary or thyroid glands
complications from surgery
ovarian failure
ovarian cyst
autoimmune diseases
medication
drug use (licit or illicit)
syphilis
pregnancy
obesity
depression

Diagnosis can't be done over the Internet, but requires a thorough
physical exam. A doctor might look for signs of hormonal problems
(such as unusual hair growth) as well as get a complete medical
history and have blood tests performed. And of course there'd be a
pregnancy test, since pregnancy is possible even when using
contraception.

Following are the sites, many of them written in technical language,
that had the most information:

Advanced Fertility Center
http://www.advancedfertility.com/amenor.htm

eMedicine
http://www.emedicine.com/ped/topic2779.htm
	
Methodist Health Care System
http://www.methodisthealth.com/WomensHealth/gyneamen.htm

Health A to Z
http://www.intelihealth.com/IH/ihtIH/WSIHW000/9339/9443.html

Hospital Practice
http://www.hosppract.com/issues/1998/07/dmmbrau.htm

Finally, I would urge you again to discuss your concerns with your
doctor. The information provided here can help you understand the
possible things that are going on with your body, but only thorough
professional attention can answer concerns with certain.

Best wishes,

Mvguy-ga

Thank you very much for your help!

"...it is not unusual for the body to take 3 months to get
'synchronized' after going off the pill. In rare instances, it may
take as long as 6 months."

http://www.fertilitext.org/p1-101/the_pill.html

is it at all possible that there is something wrong with my ovaries? 
I recall that possibly coming from the mouth of my doctor.

My eighteen-year old daughter finally went on the pill to start normal
periods after they had been virtually non-existent since she started
menstruating. She was on the pill for nine months, and recently went
off to see if her period would continue on its own. I was also worried
about possible long-term ramifications of the pill. She had one,
scanty period (of two days) and that has been it in the past month. We
are still waiting to see what next month will bring.

 Before she went on the pill, the doctor put her through a battery of
blood tests to determine hormone levels and rule out other disorders.
Most everthing showed up as normal, so the pill was used to
"kick-start" her period and keep it regular.

 Did you ever have a series of tests to determine your hormone levels?
They can be expensive, but if you have insurance coverage, I would
recommend talking to a different doctor who will spend some time
talking to you. A female gynecologist will often take the time to
listen to your concerns. If you do not have insurance, they will often
charge you a lesser amount for the testing.

 I would definitely recommend getting a second opinion at your age,
especially if you are sexually active. It is important to have a
thorough workup to rule out any abnormalities.

 Good luck!

Obviously, your doctor knows much more about your situation than a
stranger on the Internet can know. If your doctor believes there is
something wrong with your ovaries, I'd listen to his or her advice on
the matter. However, as indicated on the page linked above, when you
discontinue birth control pills, it is not unusual for several months
to elapse before menstruation resumes.