This is the one I use: I've been using it since the end of March, and I haven't paid anything for it.
I actually turned off a bunch of features- it'll tell you (if you use its database- US based- or have all the information to enter for your own foods, which I don't in a lot of cases) the complete vitamin and mineral profile of foods- I disabled almost all of that because it confused me, and left it with the information provided on packets (calories, protein, carbs, sugar, fat, saturated fat, monounsaturated fat, polyunsaturated fat, sodium) plus water. (You may also need to know American words for things- so courgette= zucchini, for example) I enter my processed foods and recipes, and use the program's database for things like fruit and vegetables. It asks you to enter your food in grams, so you may want to invest in digital scale (I got mine for 10 pounds at Argos, although full price it's 15. Seriously, best 10 quid I've ever spent and if I had to replace it I'd spend the 15 in a heartbeat). I do weigh all my food, and recommend it, but after awhile I've started to get a feeling for what a certain weight of food looks like, so I could probably guess if I had to.
Other programs that people talk about here are myfitnesspal and fitday, but I've only ever used cron-o-meter.
I'd keep this diary, personally, show people the turnaround (or how you adapt to a healthier diet). It'll be good to see.
I try to treat myself in other ways. For example, I eat a lot of berries. Growing up, they were always a treat food, once in a blue moon. They're actually cheap enough for me to afford, but they were expensive when/ where I grew up so I view them as a delicacy, and enjoy them. They have somewhere between 20 and 25 calorise per serve (80g), so they're excellent for the calorie count, but they give me a psychological boost, if that makes sense. I also look at low calorie alternatives to my treats- so when I get a chip/ crisp craving, I incorporate some roast potato (the way I make it it's about 200 calories/ serve- which isn't ideal but it's better nutritionally and calorie wise than tearing my way through the crisps in Tesco) into my next meal. I know from my experience telling my brain "you can't have any..." of whatever it wants is a good way for me to go crazy and possibly have a big binge.
Congrats on the weight loss

That's excellent.