Hey first of all *hugs* :gen126:
Remember that lean muscle weighs more than fat because of its density. Even starting to walk more would make your legs more toned, but make it look like you lost less weight.
Its not uncommon to get a different reading from the scales, relax, 1lb is going the right way. Its hard but just think you have done it! lost 1lb more than you would have before you started. Got slightly fitter and healthier than you would have say watching tv instead of going to the gym. Look at it long term, its going the right way.
You are choosing to loose some weight and your hard work is paying off!!
I understand why you are disappointed, but learn from it, then move on, new week new chances to loose weight.
There could be a number of reasons, maybe even though you stuck to the calories your body stored more of it. are you eating healthy food, mostly veg and protein?
Maybe your muscles have stored water because of the gym. I'm assuming your a girl from your name, what time of the month are you at, you could be starting to get that bloaty once a month weight. I start to get bloaty from ovulation week right till after my period so for two weeks a month I weigh about 2lb more lol
Also depending on why you were sick and what you brought up, your body might have panicked gone into famine mode and started storing stuff again. Also if you have been ill or hung over that could make a difference. I mean its a good survival strategy if we were not in a country like the uk and we needed to keep fat stores for when food is low.
Its quite complicated. like I said, 1lb maybe disappointing but it is a step in the right direction and its one step more than if you were not dieting. There will be loads of steps, and it wont be easy. But you have started! keep going and it will get easier, it will become routine and normal.