The snacking does not keep your energy/concentration levels up - it is responsible for your fluctuating energy/concentration levels.
As you are off work I highly recommend you try the 18:00 - 12:00 fasting now - i.e. only eat between Midday & 18:00.
You will probably be amazed how good & consistent your energy/concentration levels are in the morning before eating.
You may feel a little hungry at times, but just drink water (no coffee) & prepare to be surprised at how much better you feel overall.
Caffeine borrows energy, it does not provide it. You will have to pay it back.
If you think you can’t start the day without caffeine, then like an alcoholic you need to admit you are an addict & are controlled by an addiction. Once you accept it you can then work to fight it.
Drink the water! Just pure thirst quenching without any temporary up followed by a down.