In case it helps (though the actual weight loss numbers would vary from person to person) ...
You say that you are nearly 2 metres tall. I put the numbers into the BMI calculation and that suggests that you are about 1.98 m (6' 6") tall. 108 kg (17 stone) is quite heavy, but for someone of your height it isn't
terribly overweight. And as suggested above, BMI isn't the best way of choosing a target weight anyway, but assuming that you do want to go by that and get down to a slimmer BMI of 23, you would need to reduce your weight by 18 kgs.
I lose approximately 1/4 kg in weight per 100 kms of cycling providing I don't eat or drink extra to fuel the cycling. (If I were riding 4 x 25 kms I could do those rides without extra food. If I rode 1 x 100 km I would have to eat more, so from a weight loss perspective, lots of shorter rides are better than fewer, longer ones.)
If you absolutely insist that you just want to do lots of cycling to lose the weight and don't want to change what you eat and drink, then here are the numbers for me: 18 kg = 18 x 4 x 1/4 kg = 72 x 1/4 kg. That corresponds to 72 x 4 x 25 km of cycling
I would have to do about 288 rides of 25 km to get that amount of weight off. 7,200 kms! To translate that into the 11 mile commutes ... 7,200 kms = 4,473 miles. 4,473 / (11 x 2) = 203 commutes (to work and back).
I think that illustrates why it is taking you a long time to get the weight off solely by commuting on your bike, and why taking another look at your food and drink intake would be a good idea!
You don't have to count calories. Just decide that you will not drink alcohol (say) 4 nights a week and don't drink to excess the other 3 nights. As for food - categorise it into Healthy/Calorie-dense (eat/drink in moderation); Healthy/Lower-calorie (eat/drink as much as you want); Unhealthy/High-calorie (eat/drink sparingly as occasional treats and don't binge on those occasions).