Feeling lost. Please help.

Hey, guys. I don't really know how to start this off, but bear with me, cause it's gonna be a long one. I'm almost 18, and I feel like, from what I matched from the symptoms, that I've had depression for quite a while. Lemme first somewhat describe how I feel. I have bad days, okay days, and some rare good days. Even then, there's always this uncomfortable underlying blend of frustration and helplessness. A lot of times, I find myself wishing I didn't have a family to live for, that I could just end it, go to sleep and never wake up. I often daydream about if I got diagnosed with a fatal condition, about how relieved I'd secretly be about my life ending. Some days I don't feel like anything, sometimes not eating despite being hungry, and my motivation couldn't generally be lower. You know what it is. I'm not diagnosed, and I sometimes tell myself it's probably all in my head and I'm just making this up, or that I want to be depressed on purpose for the novelty or attention or whatnot. I don't know, I feel like I'm constantly at war with myself, and it's a complicated mix of emotions. I've had a rocky past couple of years, if not life, and maybe that's contributing to it. I lost two close family members in recent years. Now, I know what you're thinking, because so have I. I thought to myself, hey, it isn't easy losing people you love. You lost two. And you've been through quite a lot besides that, so, what if you're feeling is just the natural reaction? Or, here's yet another; since I'm an overthinker, what if the reason I believe life isn't worth the pain and is pretty much pointless is, not because I'm depressed, but because it's how my mind works anyways? What if the people who believe otherwise are being overly cheery and naive, and we're the sane ones? I digress. I wish I could die, reddit. If I could I probably would, but there's a lot holding me back. And I feel like the most ungrateful son of a bitch in the world for feeling this way. Besides the sporadic ups-and-downs, which pretty much everyone has, I have a lot to be thankful for. I'm from a financially sound background, I have a loving family who I'd die for but not on, I eat good food, wear good clothes, do things that not every person has the luxury of experiencing and so much more that the everyday person takes for granted. Why the fuck am I feeling this way? What is wrong with me? I'm a horrible person, and I'm so ungrateful. People would kill to have a stable life like I do, and yet I still want to die. Recently, I talked to a friend about this, and they were really supportive and recommended I go see a psychiatrist. But I'm not sure about it and I'm double-minded. Some stuff is just holding my feet back. What if I am just tricking myself into feeling this way? What if it's a lie? What if I'm just being a sissy, or a drama queen? How am I supposed to talk to a stranger about this? I don't know how to feel anymore, and what to think, reddit. I'm never happy anymore, not truly. Momentarily, yes. But then I go back to the usual sickly shit. If someone can just say a few words that might offer some clarity, or even empathy or encouragement, I could use some. Thanks. P.s This is actually the second time I'm posting this, because the first time I did not a lot of people saw it, and I'd still like some more thoughts on all this since this is the first time I ever made a post that pours my heart out like this.