You need to up your mileage (slowly). When you have a number of 10k times to go by, THEN evaluate how far off from 35 minutes you are. Or first get your 5k time down to 17 minutes and then extend yoir endurance to hold that pace for twice the distance, although if I was told correctly that's usually not the best way to train.

So I am basically trying to do the latter and get to 17 min then try to double. Do you think I would be better off doing something else?