Well done for the weight loss lou1973!
That's amazing and will pay dividends for your future health
When you say you were told you were menopausal - I presume this was from blood tests, as there probably wasn't time to see if you were going to have a bleed between stopping the POP and the implant?
I am sorry to hear about your family history of cancer and if it was breast cancer then the risks do increase if you have a mother or sister who have had the disease and also if it occurred when they were younger ( I read this somewhere recently).
Depending on the circumstances HRT may not necessarily be out of the question, but would need discussing with a specialist - as Dancinggirl says you are very young to be without oestrogen, but I can understand your fears and reluctance to take it. If it is definitely out of the question then do ask to be referred to a specialist to monitor your bone density on a regular basis so that if necessary you can take appropriate medication to help prevent osteoporosis that can be a consequence of oestrogen deficiency. As you have lost the weight you will also have less oestrogen as some is stored in fat cells ( this is not an argument for staying overweight though!) so especially important that you keep a check on bone health.
I hope this helps and you start to feel better very soon.
Hurdity x