I am very sorry about your miscarriage. I hope that the following information is helpful for you. The MTHFR gene, as you have read, is important in the metabolism of the amino acid homocysteine. Variants in the gene are inherited. You indicated that you have copies of two different MTHFR variants (compound heterozygous). This means that you got one copy from your mother, and one copy from your father. You and your siblings share the same mom and dad, so this means that each of them has a 25% chance to have no MTHFR variants, a 50% chance of having at least one, and a 25% chance of having two variants like yourself.
What to do for women with MTHFR mutations who are trying to get pregnant or who are pregnant is not well established. The one universal recommendation is to take folic acid supplements. How much should be established between you and your doctor. Depending on the person’s medical and pregnancy history, other treatments such as taking other forms of B vitamins, baby aspirin, or low dose blood thinners have been reported. There are just as many studies that state these mutations are associated with a variety of problems as studies who find no associations at all. It is very confusing for patients and healthcare providers. What is known for sure is that these mutations can impact your homocysteine level in a negative way. Taking folic acid may help stabilize the homocysteine. Having "normal" levels of homocysteine is important for you health.
You may wish to consider visiting a genetic counselor as well to learn more about MTFHR, how it is inherited, and to discuss the pregnancy and other health implications with your family. You can find a genetic counselor through the National Society of Genetic Counselors.