Shoot them back and try to manage the wave to where you're not going to have to shoot while they're not, and spend mana if you have to to avoid walking on their side to get a caster minion. Getting fucked up isn't worth 15 gold.
If you do not let your opponents know that you're going to hold your own they'll walk over you. You get shot up 3 or 4 times for free and your lane is over. That's how easy it is to lose lane. You either establish that you're going to fight for the lane or you lose, that's all there is to it.
That's why you'll have those matches where you feel helpless and you're just stuck on your tower because their bottom lane has all of the pressure and control even though everyone is 0/0. Your lane gave away that you were either less experienced or scared and then they just took control.
Should i start trying to zone out players and harass them too
Yes
i rely on my team mates
Do not do this is solo queue
The most important thing to realize about league is that it's not about passively farming. It's about removing gold from the other team while gaining gold for yourself. If they can't get close to minions and you have free farm, you're gaining a lead twice as fast and they're worthless.
A lot of the difference between higher elo and low elo in the laning phase, not so much the difference in game knowledge etc., is that high elo players are confident and aggressive. Getting to the point where you have free farm and their laner is a hobo is the only goal.