The best way to get back to Coastal Forest base camp is to retrace your steps. Reach the area where the bunker is and where you got the bow, the take the path leading south.
At base camp, interact with the campfire. Notice that in the meantime you've gained your first skill point (each level up costs one point), so it's a good moment to buy Lara some new skills. When you're done "shopping", close the base camp window (reward: 150 XP).