Does anyone know of a healthy diet that helps you drop weight fast?

Im 5ft7 and my typical weight is around 135lbs. For some reason I have gained up to 149lbs just since july of 2008. ( i think it has something to do with a very bad miscarriage) anyway, I kw thats not a huge amount of weight but its enough to bother me and i really dont have the money to get bigger clothes. the only thing is that i have mild heart problems. ive tried major calorie restriction in the past and it made my heart flutter like crazy,so anything i do has to be pretty healthy. I dont eat anymore than i used to and im a very healthy eater. I get lots of exercise with my 2 year old daughter. I just dont know what to do to lose these extra lbs, and ive tried to be on a diet but it seems like i keep gaining weight.