C-172 pilot reported NMAC with King Air on approach to land.

Narrative

I was coming in to land after a long IFR cross country. I entered the traffic pattern; on the 45 degree left downwind. There were two other 172s that had just departed on the downwind to the southeast before I made it to the downwind. There was also a medivac helicopter transitioning east to west on the other side of the pattern at 1000 ft. MSL. I go to call my base and then; final. Once I call final I hear Aircraft Y final Runway X. I ask Aircraft Y do you have me in sight and hear no reply. I then proceed to call I'm going around; since I assumed he was behind me and would be closing in fast. On the go around I hear a Pilatus call he's on the downwind and follow after him to a full stop landing. When turning my crosswind; I ask the Pilatus if he heard the Aircraft Y make any calls and said he heard nothing. The now King Air on the ground who identified himself as Aircraft Y said he made a 'few' calls and that ATC let him go to CTAF late. I don't say anything else after that and just focus on landing safely.Some things I learned; was to not assume; a bigger or faster aircraft is not going to go around for a 172 no matter what. I always join the pattern when there is other people due to this exact thing happening and ending up with a mid air collision and lives lost. The Pilatus joined the downwind like he should of at the 45 degree. The King Air should have known from ATC that there people in the pattern and chose to continue the visual straight in. The direction they were coming from had them set up perfectly for the 45 degree left downwind. I wish that large aircraft coming into a untowered airport; would say the aircraft type like in this instance King Air so and so instead of the operator name. When multiple people are calling positions on the field Aircraft Y doesn't stand out to my ears like hearing King Air. It's very easy to miss a call when in the pattern as well due to workload or checklist no matter the aircraft you're flying. I also wish that flying the pattern when other traffic is present; would be stressed throughout one's aviation career no matter how big or fast you are. I plan on doing aviation as my career and am currently working on my commercial. Luckily nothing bad happened out of this incident but it was enough to make me feel quite uncomfortable. I'm still learning and growing as a pilot and plan to keep on doing so. I definitely learned from this experience and am glad at the decision I made to execute the go around promptly.