How do you know?

How do you know when you have anxiety or depression? I just am curious. I dont know how to tell or if the ways I am feeling would be one of the two or even both. I am not suicidal at all. My life is great and I could never dream of leaving my loved ones behind. I have lost a few family members to suicide and I could never be the one to cause more pain on my family. I just sometimes have feelings and I just wonder if they are anxiety or depression related. I am scared to talk to my mom about it to see if I should be put onto some medication or something. (I am 18 so I know I wouldn't need to tell her but it would be something I would do). I just dont know what signs to look for. If anyone has anything they can say to maybe help me figure it out. Thank you.