When I started commuting (12m round-trip) I was a ravenous beast and would bring a pack of oatmeal with me to make at my desk because adding 60 miles a week to my cycling (making it 150~200miles/week total) made me super hungry. But after a while your body gets used to the load and in a few months didn't need any extra food as the body became more efficient to the task.
Also, are you getting enough sleep during the week? Can you add another 30mins during the workweek of sleeping so you don't build up a 'sleep debt', almost everyone doesn't get enough sleep anyway. As any physical activity increases you should also try to increase the amount of time you spend sleeping.
Allow yourself one or two days a week where you don't have to commute by bike and take the bus or get a ride from a co-worker etc. and make those bike days 'optional' if you feel good then maybe ride. But don't feel obligated to do it. Then you mentally only have to concentrate on communing probably only 3-4 days.