Is this too much food that I ate today?

That's only about 700kcals. You will lose weight if you carry on eating like this but then you will gain it all back again once you start eating normally. You need to add more protein at lunchtime and not just eat fruit which is just sugar. Eating protein is great for losing weight and speeding up your metabolism so in the long run you'll lose more weight and keep it off. Have a healthier lunch with some protein and add some more fish at dinner. You need some fat in your diet too so maybe add some butter to your toast. Your breakfast is very filling and healthy. I was anorexic for years and I've learned now that starving yourself will wreck your metabolism. If I want to lose weight now (when I genuinely need to) I eat little and often, no sugar and protein at every meal. Plus exercise. A trainer taught me this and it works better than starving myself did, quicker results too. You really need to keep your metabolism working if you want to be slim. You wouldn't put no petrol in a car if you wanted it to go fast. You wouldn't put the wrong kind of petrol in either as it could damage it. Make sure you put the right fuel in your body and you will be in great shape. I also think you should check with your doctor to see if you even need to lose weight.