As a Bronze Zerg, I find that whenever my natural is blocked/cannon rushed by a Protoss opponent that by the time that I've dealt with it I'm a long way behind. Then subsequent 2-base pressure is the coup de grace.
In my last ZvP game, I went 14 pool with the aim of going 15 hatch. When the Pylon blocked my Natural, I pulled 2 drones, whilst I waited for my Pool to pop, to kill the Probe and attack the Pylon. A cannon was placed before I managed to kill the Probe, so I pulled a further 2 Drones, so that I now had 4 Drones attacking the cannon. The cannon was cancelled at the very last minute, so for very little cost and effort from the Protoss' behalf, I've now lost a considerable amount of mining time. I eventually cleaned up the Pylon and took my Natural and droned-up like crazy, but around the 11 minute mark, when the Warp gate pressure came I didn't have enough to hold it off.
What's the correct way to deal with this sort of strategy? Is there any way to punish a Protoss that just goes FFE behind this?