I'm 18 next month and I straight up just don't know what to do with my life

Probably a relatively common thing I know, but I want to know whether other people feel as utterly lost, uninspired and unmotivated as I do towards transitioning from a kid to an adult

I'm relatively privileged I think too as I've never worked a day in my life yet, had below average (but good enough for UK college) grades and yknow constant access to food, water, heat and other not as important for survival stuff. But life still feels like not really much of anything? Like I don't think I'm suicidal exactly, and I've been to the doctors after bordering on harming myself and was prescribed sertraline, but I just feel so unmotivated all day when I already don't do anything.
 I used to go to college last year but I had an especially bad depressive episode (which is why I went to the doctors, I've had these before just not as bad) which started from the summar before school and just got worse as time went on until I wasn't able to even sit in class without tearing up from thinking about how fucking atrociously I'm doing in my exams and lessons and at making friends, my mind would literally race and I'd be sitting there with blurred vision from my tears trying not to have anyone notice me. 

even though I try to take the sertraline correctly I keep forgetting and either missing a few hours or remembering the next day that I even forgot. Which might be why I'm not feeling so great since you're supposed to take them at the same time each day :-/

as I briefly mentioned before, I used to have these periods consisting of a couple of months of just feeling worthless and lying in bed all day, and I either thought not much of it in terms of mental illness or in terms of how grateful I should be idk so I didn't tell my family or friends. But with this recent one I finally spoke up to my sister who seemed somewhat understanding at first, telling me how she "knew there was something wrong" (even though she never asked me about it) but seemingly forgot about how bad I feel (same with her boyfriend) and sees everything I do or don't do as being lazy or ungrateful or nasty. Things that are literally like the main things depressed people do like not care about their hygiene, have no energy for conversation or activity, be easily upset or irritable etc. I don't understand why she doesn't understand either since she's also taking sertraline. And my other sister just doesn't even seem to care, and is mad at me for "not telling her" while at the same time calling me a "thick twat" for not finishing college when I mentally couldn't take it anymore. I feel like my mom was possibly just born in a country and generation that doesn't care much about mental health, so she doesn't really understand, but she tries to be caring, but like the other two she sees my actions as lazy even though I'm trying. My dad, who I'm thankfully away from hopefully forever after telling my family about him sexually assaulting me, reacted the worst after word spread that I'm unhappy, and screamed at me about how I'm not depressed, and how I better get a job or get the fuck out of the house.

In terms of the initial paragraph about feeling lost, I just feel like with only average GCSE grades jobs are going to, and are because even fucking McDonald's won't hire me, be hard to find. And I just moved to a place where the nearest college is an hour bus away, and doesn't have any courses I'm interested in. And if I were to go to the college I went to earlier it would be 2 hours, not counting the time spent between buses at a stop. So I feel like at this point it's too late for me to be able to go to college, unless I grow a pair and move out on minimum wage with absolutely nobody to help or live with me.

Maybe the best thing to do would be to finally land a job at a local supermarket and make friends, but I'm so afraid I won't be able to, since at college the only friend I had from when I was around 12 made like 9 friends in 5 months, and I couldn't bring myself to hold conversations with them, not because I didn't like them, but because I just didn't have the energy for it and I thought of myself as low tier trash whod be better off ignored. I'm so afraid that if I finally work I won't be capable of making friends, especially since it's not guaranteed the other workers will be my age, or have similar interests.

I feel just at a complete loss, and with no support from my family apart from financial and having a roof over my head and food to eat, my inability to go to college and the seemingly small choice of job opportunities and said jobs not employing me, I feel like I'll at some point spiral further down and not be able to keep going with anything anymore :-(