Not happy at uni, what should I do?

I can completely empathize with you, I am currently studying a biology/psychology degree whilst living at home, ideally I would work with horses but have felt that the job opportunities are too few or too badly paid.
I considered veterinary nursing but like you felt it didn't challenge me enough academically. Currently stuck feeling like I'm treading water until my degree is over. Researching an equine science degree to change to but am scared of dropping out as I've always tended to equalizing dropping out to failing its so frustrating living at home (would love to spread my wings but the financial benefits of living at home are great) AND studying something I find ok for now but definitely don't see myself doing in the future.
Can anyone shed any light on what to do? Tying myself in knots trying to figure it out!

If you aren't happy, then leave. Otherwise you'll end up doing a degree with poor grades. Also, when you do finally decide what you want, if that means going back to university, you won't be funded again if you complete a degree.