IANAP but wanted to say this - Same argument could be made for EM force. There is electric field around a charge but only when you place another charge the two charges attract or repel as per electromagnetic force. That way gravity and EM seem to be similar. But gravity does seem to be different as it can be thought of as not a force (in agreement with your physics teacher). It curves space and time and objects just move along the geodesics (straight lines on curved surfaces). So gravity gives rise to space time geometry. Once that happens, you can stop thinking about gravity as a force. Worth emphasizing again - IANAP.