Could I have a mental illness?

Since I was little I've had severe OCD and Panic Attacks. OCD examples; not swallowing my spit because I brought myself to believe that if I did my family would die. Always counting my steps, turning over objects a certain amount (even numbers) of times that would usually equal 4 or 5. 4 being the members of my family and 5 being the members of my family and my pets... I would be saving their lives. I still do this frequently. If I try to stop myself from being OCD, I get very uncomfortable (I clutch my hands and try to think of something else) but it drives me insane. Lately it's been getting worse, I've been in a bad mood all week and I'm depressed. It's exhausting, having to deal with all the thoughts in my head... calculating and adding up letters in words-- and all for what? Nothing. I try to stop myself from doing this but it's like I CAN'T. I've been snapping at people all week because I'm just fed up with myself, I hate myself at this point. I have bad thoughts of killing people and then I feel dirty because of the mistakes I've made in my life and I am just unhappy. Sometimes I find myself talking to myself, just having conversations with someone I don't know and about a situation that's never happened to me. And when I catch myself, I'm like... OK STOP, I'm exhausting myself. What should I do? I might go to a Therapist... I'm just wondering if there's a name for my problem? Oh and if it matters at all, I'm 17.