Vix20678
I am so sorry for your loss. To lose both parents within such a short time must be horrific for you. 
I lost my dad 9 years ago and I found my mum dead at the end of January. I thought she was fit and healthy too. She wasn't on any medication, would dig her garden continuously and went out for hours every day. She'd been dead for a few days when I found her. It was her funeral today.
It's been such a surreal time and waiting for a post mortem then over a month for a funeral has been awful. I can understand your total shock. My mum had a post mortem, thankfully just a CT post mortem which showed Ischaemic Heart Disease and Atherosclerosis. It's surprising she displayed no symptoms like shortness of breath. It is really hard to find a parent dead and have so many unanswered questions. Although I would have preferred to be with my mum when she died, it would have broken her heart to say goodbye to her children so I have to be glad she didn't have to do that.
I have my siblings but I feel completely lost now too. I think losing your second parent isn't just about losing that one, it's about becoming an orphan, no matter what your age is.
I really feel for you, being an only child. There are advantages and disadvantages though to having siblings.
I have turned into a complete worrywort precisely because I have siblings. It's made me realise we are now the oldest generation and, I know it's silly, but I'm so scared by the thought that I may have to lose my husband or siblings one day.
I hope you have wider family and friends to help you through this terribly sad time.