A size 7 shield, requires 4 torps with reverb cascade to drop (4), unless it is engineered to be tougher (Thermal Resistant, or Double Braced, or both, however even with BOTH the shield drops with the 5th torp). Torps are SLOW 200m/s. out run them, as point defense will likely NOT destroy torps (their HP is off the charts), or fit a turreted Frag Cannon (engineered with Screening Shell). The "Grom Bombs" have an eternity of recharge time between their effects... don't panic, replot, reengage fsd (pay attention, so u see their usage and connection). I am unsure if the effect is delayed PER SHIP, or if it is delayed PER CMDR (firing them), and such careful planning & coordination by the gankers MAY NULLIFY THIS NERF MECHANIC (i havent tested this yet). But... the main issue lies with, YOU are a VETTE, not a Farragut Class Battlecruiser, 4 ships are not a cake walk, even 4 sidewinders (properly engineered). You are not invincible, learn your & your ship's limits, fly within them. Gankers are a thing in ED, get over it. I wont sit here and tell you to "Git Gud CMDR", but that may be the remedy. Corvettes make CMDRs feel like the KING of any PvP encounter. High DPS output, yes... But less than an Anaconda, with the same maneuverability as the Conda... same speed as the Anaconda... Cutter is a Shield Tank, Anaconda is a Hull Tank, the Corvette is a DUAL TANK. That's it, period. Cutter has SPEED, where the other 2 do not (excel in maneuverability instead). Long story wrapped up, "Gankers use Medium ships & numbers for a reason... They're better. Fly in a Wing, or don't fight a Wing without a Wing, YOU WILL LOSE (unless they suck... lol)"
Edit*
Maybe you should invest in a T-10, as it is THOROUGHLY UNDERESTIMATED, and may fit your combat style better, it is quite the beautiful (and deadly) machine in the correct hands!!!