It's normally easier said than done but try as hard as you can to not compare your own situation to other people's in terms of 'life progress' and shit like that. In terms of your career, house/flat, car etc, you'll probably make better progress and feel better about it in general if you set small targets and goals for yourself. Keep them realistic and manageable, whether it's putting away a wee bit each month for a deposit or focusing on the positive things in your life. Also, don't give up with the deposit thing or the weight loss, 1320Lichtie advises that you keep looking around so I'd go with that, the first bank/mortgage adviser might be talking pish.
Also, as others have said, that weight loss is a fantastic achievement, putting on a stone after losing three is brilliant, keep it up!