How can you tell if you have depression

I personally don't believe in self-diagnosis on myself since I don't want my mind tricking me into thinking I actually have what I don't... I'm just wondering if there's any way I could have depression? I don't know if I do or not, since I live in such a nice house and have amazing family, friends, and boyfriend so I feel like I shouldn't be depressed because of those things. I have just been suicidal lately and have recently attempted it, and some days I'm just neutral-sad as if all I wanted to do was cry and do nothing and just feel ashamed of myself and I just want to end it all.
Can't tell if this is either depression or if I just get sad a lot, and I'm not sure if suicidal is linked to depression. Is there any way to accurately know if I have depression or not? 
Please leave no pity comments on how you're sorry for me, I'm sorry if it sounds rude but it just makes me feel worthless even more for some reason