Do i need help

I think i need help in some sort. I'm really struggling, haven't spoken to anyone about this but feel like I should. I've been really struggling with my mental health for a few years now, I'm 18 btw, but idk what to do about it. To put it into an analogy it's like I'm in the ocean stranded, but then a wave comes crashing over my head and it sinks me. I then struggle for a while to get myself out of the wave and can breath again then when I'm finally feeling better (like ik I can get through this) another wave hits and it's harder to get up this time. There is no particular event to make this feeling occur however it still does. There are people out there with big problems and get through them so why cant I get through just not being happy. I've had suicidal thoughts every night for 2 years but I can't seem to bring myself to do it. I don't ever talk about this but feel like it's becoming a necessary to get some opinion on this that's why I'm doing it on reddit. Am I just being a pussy or do I need help, any message or feedback would help thank you