Have you talked to your doctor about this?
There are some very good books about what to expect while you're expecting. The most famous one is actually called What to Expect When You're Expecting.
You can often find copies in thrift shops as well as in the library - and bookstores.
Also, consider joining a local group of pregnant women to discuss what's going on with your body (the hormonal/chemical changes in your body effect your appetite and cravings) and your emotions.