Loose weight is largley about diet, the gaterate you have in the morning probably has more calories in it than you burnt on the ride in and personally I prefer to eat my calories. Having said that its got mineral replacements but is missing magnesium. For weight loss, why don't you try something different in the morning, perhaps 2 or 3 weetbix with fruit and low sugar yoghurt. Replace the gaterate with plenty of water, mild dehidration can make you feel hungry when you are actually thirsty, btw I'm assuming you have a water bottle on the bike and drink before you get thirsty?
The calorie saving from the morning will provide you some buffer, so if you get the munchies, you can score a piece of fruit for a snack. The fruit will give you a bit of sugar along with a bunch of good stuff.
Why soya milk? I use it sometimes because I don't produce very much of the enzine that breaks down lactose, but if you haven't got a special health issue, just use normal milk. There is debate as to whether soya milk is bad for you. Besides you can score milk from the office fridge usually.
Muscle Strength. When you exercies muscles you damage the muscles and then the body repairs them, using protein to repair them and make them stronger at the same time. To be honest, I'm not sure how much protein you need to repair after cycling, I'm guessing that the protein in the weetbix and the yogurt (if you go down that path) is sufficient in the morning and you have protein covered at lunch and dinner, so you are probably ok there. I lift weights in the morning immediately after riding in, so I damage my muscles much more than you and need more protein.
Lunch. Much better than mine, you could mix it a bit, fish gets boring after a while. Check out the carb content in the rolls, I'd bet that there are more calories in the rolls than there is in the filling. More filling less boring bread.
Dinner. Sounds pretty good. Not much improvement. Switch to Basanti rice if you are not already using it, Basanti has heaps less carbs than Jasmaine.
Commute. 6 months in , you are going great guns. The first 6 months is the hardest, as the body has to adapt. You will find that you will advance less rapidly from now on, but will continue to improve. BTW, what actual route are u riding, I'm thinking of the hills, they can be used to your advantage to mix up what you do. Sometimes on the way home, I push myself to the limit up the hill and then have a rest before tackling the next hill, a kind of informal interval training to build muscle strength and I'm still getting the aerobic content in there as well.
Get some ideas of others, what works for one doesn't work for everyone and make the changes one at a time.
Let us know how it went at the Doctors.