You should always go town. I usually wouldn't go on the outside of the 1 line like that, but someone has to cover it so you were alright.
You guys were going to lose town regardless, but you played about as poorly as possible. You were sidescraping against the IS-7, but you didn't do anything, you just sat there. Load gold, back that booty on up, aim, and you should be ok. That's not what really annoyed me though.
When the 121 initiated the fight against the IS-7 you threw away the opportunity he gave you. Instead of helping the 121 focus down the IS-7 you decide to try and hit the 1390 down the road with your broken gun, multiple times. 1390 wasn't going to do shit to either of you. When your gun is damaged fix it. When you are backing up don't turn sideways. When you are in a 2v1 and your team mate starts pushing help him.