Is it normal that i never leave the house and have no motivation?

I am 18 and I never leave the house. I want to go out though, I always decide that 'tomorrow I will go and search for a job/go buy something' but it's very rare that I will actually go and do it the next day. I've needed to deliver a letter for over 2 weeks now, everyday I think to myself that I will do it but it's still not been done. Getting a job is also an issue, I haven't been employed since Christmas and I'm not doing all that much to find a job. I want to, trust me, I do. I don't want to be lazy and unemployed forever but I find it extremely difficult to motivate myself to go outside unless I want a cigarette or buy alcohol. I've also lost contact with all my friends and I don't try to maintain friendships anymore. I have feared for a while now that I have something wrong with me mentally, I've questioned social anxiety or even depression because I hate dealing with people and I can't be in a big crowd of people, it terrifies me. I also have these moments where I get extremely upset/depressed and it makes me hate myself and feel even more disgusted with my appearance than usual. I don't know what I can do to help myself or if anyone else can help me.