Student pilot on downwind at a non towered airport reported they performed a 360 degree turn and caused a NMAC with a departing helicopter.

Narrative

I am a student pilot who flew from ZZZ to THV on the morning of Date on arriving at THV; I landed on Runway 17 for a touch and go and took off. I turned downwind; I heard the call from a Helicopter that took off from THV on Runway 17 who called out they are east bound. On the downwind leg; I heard a radio call from another aircraft making a direct GPS approach to Runway 17. I was unable to estimate the time taken for me to complete my downwind/base and final and elected to do a right 360 to let the other aircraft time to complete their approach. During my right 360; I noticed on the GarminG3X traffic system that the helicopter was about 400 feet below me behind me; as I was moving in the 360; I noticed the helicopter vertical altitude was now reporting just 100 feet below me and behind me. I immediately increased power and climbed and as i was two thirds into the 360; I did get a visual of the helicopter at my 3 O clock which was below me and flying east. The traffic alert system on Garmin G3X triggered for the event. In retrospect; i should have extended my downwind instead of doing a right 360 and kept the separation from the helicopter traffic.