It’s hard to tell the exact problem without watching and listening to you but it sounds like you’re not getting your air from the diaphragm. This is the top priority and only way to get started to get the proper sound. Are you doing it right? To tell, put your hand on your stomach area and while you blow your gut should be pushing your hand out, if not, you’re getting your air support from your throat area and it won’t suffice.
Check out the beginners lessons for this in more detail.
Johnny