You will feel some vibrations in your throat as every time you make voice, the vocal cords vibrate and they are located behind the Adam’s apple so that causes some throat vibration. However, you should fell less vibration in the higher pitch when making the Uhm and MM Sounds than when you are in lower pitch.
Try to focus the MM onto your lips, as if your voice starts from there. Pout them forward a little bit and see if this helps to lessen some of the throat vibrations. Extend the MM sound a little at the start of all the words beginning with M e.g., mmeet; make; move.
After that, Aim to speak as much as possible from the lips - this also helps to take strain off your throat and reduce chest vibration.