Should I seek professional help?

Hello, first of all I'd like to apologize as this will probably be quite lengthy... Right now I am extremely confused about how I am feeling. Very few people in my life know that I have been feeling so terribly. (I have felt this way for years and only my closest friends and my brother know). Ever since I was a sophmore in high school (I'm now a freshman in college), I have overall been very unhappy in life. I do not like to tell my friends that I feel depressed, as I have never been diagnosed by a professional and I don't want to use the word depressed if I don't really know. When I first started having these feelings, I had a very positive outlook on life, thinking it was definitely worth living. However, over the past 6 months or so, my outlook has diminished greatly, and I think about suicide on bad days. I wouldn't actually commit suicide because I don't feel like I could do that to my friends and family, but I do fantasize about it nearly every day. I tend to be extremely irritable with my friends, which makes me feel bad because I snap at them, and make myself look like an asshole even though they mean the world to me. I am reluctant to try to talk to a professional for many reasons. First of all, I am 18, live with my parents, and I really don't want them to know anything is wrong. They've done everything they can to give me a worry-free life and I would feel so terrible if they had to worry about me being ungrateful for it all and still feeling the way I do, even though I truly do love and appreciate the struggles my parents have gone through to provide for me (my dad broke his back, lost his job, and hasnt been allowed to work because of it and my family has had financial troubles ever since). The biggest problem I have with all of this is that I can't say I really have a problem with how I feel. Over the years I have grown perfectly fine with being so sad that every day is painful. I'd even go as far as to say that I enjoy it... I haven't explained to anybody in full detail how I feel, and nobody knows that I think about suicide and death every day, and wouldn't really care if I ended up dying. There are many things keeping me from trying to seek professional help. First of all, I have always had a really hard time asking for help. Just writing this thread is filling me with feelings of embarassment, because I can't even manage my emotions without asking for help... I have tried joining this site and making this thread multiple times, but ultimately chickened out every time. I have done my research on depression and I convince myself there isn't anything wrong because I don't have all the problems people with depression typically do (I don't usually have trouble getting out of bed, and I don't have a hard time concentrating on things like school work (although I am very lazy and forgetful)). Because of this, I convince myself nothing is wrong with me and so I rule out seeking help. This makes me feel even more guilty about my feelings as I know people in the world obviously have it worse than me, yet they don't mope around like I do. I have an even harder time asking for help since my parents have financial troubles and I don't want them to try to spend money to help me. I'm sorry this thread was all over the place, if you have any questions I will try to answer them as quickly as I can. I am more or less just looking for opinions. Do you think I should seek professional help or just keep going on like this? It is at a point where my family is starting to notice something is wrong (I'm usually good at hiding it) and I hate that they have to worry.