Have you seen a GP yet? They can give you a few tests to make sure you're going alright and tell you if your electrolyes are out of wack or not. Doing a full 30 day fast is very tough and I don't think i'd do it without medical supervison as I'd be really worried about heart failure. You can stop now if you want. 8 days is pretty impressive, just don't rush back into eating. Slowly refed on juices, then fruits and vege and slowly work your way to healthier foods. If you're hoping to keep weight off before doing another fast, I would get a diet journal or join a site like MFP. Then you can track what you're eating and prevent gaining back the weight you've lost. You will gain a little though as your body will be holding onto food and wastes again, but at least it's not fat =D.
Sadly you can't completely get rid of stretch marks. There's nothing on this planet that can remove them as they are deep tissue scarring. You can however make them lighter and smoother so that you can barely tell that they are there. Just keep hydrated and keep your skin welll mosturised. Many people have a pretty good luck from microdermabrasion but for me, my stretchmarks were massive and purple. I started drinking more water, eating healthier and i would use coconut oil on my stretchmarks. After about 1 year they're silver and you can't really tell they're there.
I hope you luck on your life long journey. Don't push yourself if you're feeling to bad and if it's bad enough, please see a GP. There are many GPs out there now that understand waterfasting and will be happy to just check your body to make sure you don't have any health issues that could be made worse by a fast. Stay strong! Stay safe!