Hello I am new ish

Hello I up loaded " Myfitnesspal " to my ipad ages ago, and I used it for a few weeks, I then got food poisoning that kicked off a heart problem ( beats to fast and irregular ) so I was told not to diet or exercise un till the Dr's could slow my heart and find out what is the problem. I weighed 12st before the heart trouble, but I put on a stone in the year due to not been able to do much. The Dr told me I can start to exercise again and diet to. I have been doing My fitness pal for 4 weeks now At fist I lost 4lb the first week and 2lb the second week but the last two weeks I have but 1lb on each week. ( not sure why ) any advice would be grate My names Becky I am 32 nice to meet you all.