She is 18, her peers are now in their first year of university and she is spending her time at home watching tv or asleep.
Maybe she needs time to process everything that's caused her difficulties at College. Also emotionally she'll likely be around two thirds of her chronological age, so it would have made her feel the differences with her peers an awful lot, being expected to do everything because "at your age you should be able to" can be a nightmare for some kids with AN.
Has she any co-morbids? My DD's fatigue really kicked in as a teen and it wasn't until she was at home all the time that I realised how severe it was for her, TV and sleep was her only way of existing for a long time. Has she seen an OT at all and could you get her an appt for when lockdown's over to make sure there's no physical cause for her to be so tired, whilst bearing in mind all the extra constant mental effort involved in trying to navigate the NT world.
I just want her to be happy and move forward in her life
Right now I'd remove all expectations and pressure to decide on a future career path.
While she's at home, how about teaching her the life skills she'll need to live independently and more importantly making it fun.? Can she cook, clean, manage a household budget, know how much she'd need to earn to pay rent, finance driving lessons and run a car, basic car maintenance, keep the place clean, use domestic appliances, know when to call a plumber or electrician and how to do so, how to explain to them what needs doing, how to deal with getting an estimated cost, plan meals, physically and online shop for essentials, change a lightbulb and plugs, look after pets. Manage a bank account, work out interest rates for savings, look at household bills, discuss managing finances, explain direct debits and other payment methods. Book a holiday, plan days out, home decorating and more. By going through all of these sorts of things with her, you'll see her strengths and weaknesses and she'll be more able to see what she's good at and what she needs help with and what she feels confident doing.
There's so much more to being at home than 'wasting' her time.