C150 pilot reported initiating a go around at a non-towered airport when another C150 taxied onto the runway in front of them.

Narrative

I was doing pattern work at ZZZ and I was doing power off 180s in the 150. As I was turning base another 150 announced that they were going to take off on runway XX. I proceeded to go on the radio and say I was turning final. The plane continued to pull out on the runway in front of me. I announced that I would do a go around. It seemed like the other plane had no idea where my position was. I went over the radio and told him I was to his right about 100 feet above him. I extended my upwind to try and get some spacing. As I turned base I realized that the 150 was making a much bigger pattern than needed so I quickly caught back up. As the other 150 was landing I was turning final I almost had to do another go around but I was able to make the runway just after the other plane departed. Even after making frequent radio calls the other pilot had no spatial awareness to what I was doing and where I was. If I didn't do the go around in time I would've risked crashing into the other plane. If I don't go to the right of the runway and tell the other pilot my location there was a risk of a mid air collision. ZZZ needs a tower so this situation doesn't keep happening.