For comparison, I'm size 10 (sometimes an 8) and am 5 3" I weigh 7.7st.
I have tiny hands and wrists and have to get all rings made to measure. I am skinny, just small framed.
You say you don't know how to eat healthily @Ilovemycatalot
There is masses of info online and all the supermarkets have good recipes on their sites, usually sorted into 'healthy eating' sections.
You don't need to make complicated meals.
Just work on the basis of real food - basic things like fish, chicken, eggs and pulses, and add lots of veg and fruit.
Cut out sugar, processed and white flour things like pizza, white pasta, white rice, white bread, cake, biscuits, crisps, sugary drinks etc.