I have started most of the symptoms of menopause except the decrees in periods. I had my doctor run a thyroid test because years ago I had thyroiditis and was concerned that it might be that my levels were fine. I am very concerned about if I might be really going through perimenopause or not. I have had very severe pms and pmdd for the last 5 years to the point of trying birth control again even knowing that it gave me headaches and this didn't help. I also had a bone density test done and it showed that I had a -1.0 density in my index finger.
Early menopause has certainly genetic compounds.
So, when your mother and grandmother went through menopause early, you should not be surprised when it happens to you also. This is important to know, because you need to have your children not to late because of fertility problems later on. But further nothing is certain. Even your symptoms on this very moment do not prove that early menopause is really your future. Especially not as long as your periods are regular.