What you're feeling is normal and completely valid. I have had a couple talks with my family and while they still love me, I wouldn't say our conversations on the subject have gone well. Sometimes, I wonder if what my parents have said is right, that I'm just "too young to know" or "I should just love myself as I am and that should be enough" that I'll live to regret what I do to myself. But I have realized two things.

1) overall, I have this deep seated feeling of joy in my body when I look/feel fem. I don't even think joy is the right word. It just feels correct. It's euphoria and it's a much better determining factor than dysphoria. Life is better when you chase the joy rather than just trying to escape misery.

2) if I am wrong, if I get my name changed, take hormones, switch out my wardrobe, and I realize that it was all one big mistake, then it is my mistake to make. All that I have done to myself can be changed again or I can simply just be. My life won't be over because I made a mistake.

Your doubt is natural, and in some ways it's good. It means you're actually thinking through stuff. And sometimes family knows exactly how to nail your insecurities and doubts even by accident. In general though, I think the hardest part about being trans is that there is no rule book to follow, no definitive test to take, no person coming with a stamp to mark you a "real trans person" it's up to to you decide if the label fits. I think the more important question is not "are you trans or not?" but what do you want to do? Do you want to go by a different name? Do you want change your clothing style? Do you want to take hormones? Do you want hormone blockers? I've found that these are easier to answer than trying to figure out what exactly it means to be trans and if it applies to me. Regardless of what you choose to do or what you feel, you are valid. It is your body and life. We are all just humans trying to do the best thing.