my doctor has not done a sonogram on me since my 18th week of pregnancy and i'm going on my 33rd. i'm wondering, should they be doing one soon to make sure that my baby is in the right position??

"Why do some healthcare providers schedule ultrasounds differently? If there are any questions regarding gestational age, placenta location, or possible complications then more ultrasounds may be scheduled. Because ultrasound should only be used when medically indicated, many healthy pregnancies will not require ultrasound. The average number of ultrasounds varies with each healthcare provider. " (from http://www.americanpregnancy.org/prenataltesting/ultrasound.html)

Your baby may still change positions prior to delivery, although if he has turned into the cephalic (head down) position and dropped a bit getting ready for birth, chances are good that he will stay that way. As the information above states, different doctors prefer different timetables for ultrasounds. You might ask him about it at your next scheduled visit, but unless your doctor suspects a problem of some kind it is not really necessary to schedule one at this time. :-)