The trick to bot lane ganks is reacting according to WHEN they are happening, not after. As a mid laner or a jungler, when you see your bot getting gang banged, you should already be close in the vicinity or you already screwed up. Just running down there while it's happening from either mid or your raptor camp means you already failed and should just keep doing what you're doing.
Also, as a bot laner, you shouldn't just expect your mid laner to follow his laner, nor a jungler, sometimes you should just back off for the team. I've been smurfing in Silver lately learning Azir and the amount of rage I get for not following my laner pre 6 is absurd. I am Azir, usually facing a zed, Ahri, or Leblanc, under no circumstance would my roam help you in anyway. The only thing roaming for me would do is delay my powerspike even more and possibly end up getting me killed when my laner turns on me in the jungle or forces me to back.