Yummy, first port of call tomorrow - your local authorities PALS office. Starting your search here might be of help - www.nhs.uk/service-search/patient-advice-and-liaison-services-(pals)/locationsearch/363
Your GP is a useless piece of crap. You're in a vulnerable individual in your hour of need (be it a viral infection or a miscarriage), that is no way for a human being, let alone medical professional to treat others.
Many of us have been in your situation (MC's), and many don't feel great about future. However, with appropriate help we are soldiering on - some pregnant, some receiving fertility treatments, some getting a helping to sustain a pregnancy. We've some network of support, which is incredibly important. That is what you need now.
Everyone's different, some people benefit from counselling, some from getting the ball rolling in their quest to parenthood, some from getting some answers to questions whirling around our heads. You may want one, or all of those things, and for that to happen you have to get a decent GP, or insist your current one stops being an inadequate waste of space and gets you some help NOW.
Early MC really isn't the end of the world, I promise. Multiples are frightening, upsetting, but rectifiable. Take some comfort from the fact that you can fall pregnant (many don't develop eggs, some have eggs that don't fertilise, etc.). That's a HUGE advantage, trust me.
Miscarriages may just be a very, very unlucky run. Or there could be something other than chromosomal issues that's causing them. Many things now can be helped - endometriosis can be lasered off, NK suppressed, blood disorders kept under control, etc.
Which area are you? I know of a GOD of a doctor who deals with miscarriages (one of his specialties).
Don't get sad, turn something negative into something positive. You know - death - that's permanent. Don't try to catch up with it sooner than you should, you've years to get there.