Recurring Miscarriage with 4 times.

I have conceived 3 times in the last year (the last one was through IUI procedure). But all went in miscarriage in about 8 weeks (the 1st one removed through D&C and the other two by medicine). I have low AMH value with 0.6. My period is regular with average 25 days. This year in the February month I have done IVF as per my doctor's suggestion. But it failed. I have 3 frozen embryos. I tried again naturally this time. It shows positive but today miscarriage happens again. It was about 6 weeks. Should I go with the frozen embryos this time? Will IVF helps to prevent miscarriage? Or is there any other treatments in this regard? I am totally depressed with 4 miscarriages. What should I do to overcome miscarriage? Please help.