Worried @ 17weeks!!

So I'm going to an appointment on the 6th next month but I'm so worried!

I'm 17weeks pregnant and I'm always allllways dizzy with a headache. Even if I eat thinking it would help me it stays. When I get up to do something I feel like I'm gunna faint. I eat healthy as I can and take prenatal vitamins. I have always been heavy set but never had problems with blood pressure. I have been feeling some what depressed to the point I don't want to eat but of course I do and as soon as I eat I feel better for awhile and eat like I felt hungry. I worried people say Im fine this is my first pregnancy but it just does NOT feel right I have migraines all the time even as I speak! I'm worried :/