Air carrier First Officer reported experiencing a CFTT event on a visual approach.

Narrative

On arrival into ZZZ; I experienced a loss of situational awareness that resulted in a go-around. On a straight in visual to runway XX at ZZZ; we elected to use the RNAV as a back up to the visual. On the descent from 6;000 to 2;000 ft there was a traffic resulting in a sudden level off 50 miles from the field in a clean configuration. We became visual with the traffic at 3000 feet; 30 miles from the field in a clean configuration. To continue the descent after clear of traffic; I used the speed brakes down to 2000 feet which started a descent and called for flaps 1. We were cleared the visual and discussed using the RNAV as a back up; however we still had direct to ZZZ in the FMGC. Not realizing the approach wasn't loaded; I started to follow the flight director in approach mode. The Captain said you're low and need to level off at 1000 ft. I checked the RNAV approach again and was confused on the guidance giving me below 1;800 ft (was at 1;000). Started a climb and pushed up the thrust levers however the auto thrust was still engaged. As speed decreased I check the flaps were still at flaps 1 and called for flaps. The Captain then said let's go around and we accomplished a go around to the Tower pattern.