I've had two unusual periods in a row. both were much lighter and shorter than usual w/ almost no cramps. i'm not on bc. should i go visit my doctor?

Yes: At 23 women's periods can sometimes still fluctuate, but a pattern should be checked. The fact that you commented on not being on birth control makes me think you are sexually active. The first thing you should do is make sure you are living healthy and take a pregnancy test. Then see your Gyn with the results. All may be well! You may need some tests or you may be referred to an endocrinologist.