Hi Anon - What you may be dealing with is perimenopause - the period of time in which your body starts making the transition to menopause. While the average age at which women experience this is in their mid-40's, perimenopause does occur in women in their mid to late 30's too. This period of time can be lengthy, lasting from two to eight years, and hormonal fluctuations during this time can cause very irregular periods.
For most women perimenopause is a gradual transition period, and there's no one test or specific symptom that definitely says you've entered this phase of your life. Have you talked to your health care provider about this? Your physician or gynecologist can review your menstrual history and the symptoms you're experiencing to help determine whether you're in perimenopause. Sometimes hormone tests are done.
So, no, you're not losing it. :-) Here's additional information on perimenopause from the Mayo Clinic's health library.
Will you let us know what your doctor says and keep in touch? We'd love to hear from you again.