Honestly, if she goes to university in this state she is extremely likely to drop out. It's not got to be THIS SPECIFIC university, after all - and you're looking at a huge amount of debt to study now, so going when unsure is a very foolish financial decision.
I think you're looking at this a tiny bit irrationally too, if I'm honest - you sound like you have been so stressed by supporting her that you're also losing a bit of proportion, which I completely do understand and sympathise with. They say you're only ever as happy as your least happy child, so these last years must have been hellish. But you didn't support her so she could go to university, really, because that wasn't the life stage she was in. You supported her so she could get decent A levels, so she can, if she wants, and when she wants, go to university. You gave her choices in her adult life, and that's what our job is, as parents. You've done your job, and now it has to be up to her. And it makes no odds at all if she goes now, or in a year or two, either. What matters is that she goes when she feels she wants to do so, and that she studies a subject that interests her, because that's when people do well, and can carry a decent degree on with a future.
I appreciate that the last couple of years sound harrowing for you as her mum. But they're over now, and the reality is, she's got to make her own choices about her own life, moving forward. She's 18 and her school years are over. Adult life lies ahead. Sure, she will need love, support and sanctuary, but she has to make her own mistakes and choices, just as we all do.
You haven't wasted all that time, energy and money. She got her A levels. They're not going anywhere, and nor are university places in the years ahead. Give her some credit for managing to finish on target and on time despite serious ill health, and give her some time and space.
I also think you need to remember that she only just got her results, and if they were a little below predictions, then the tension and stress of awaiting them has now had disappointment and a little embarrassment added to the mix. She's not going to be feeling especially sensible right now, because she'll be reacting to all the stress of the past few months of revision, exams, waiting and results. Let her have her summer to decompress, and then see where you are. She may be fine about going in another month. And if she isn't, well, so what? She's 18. A lifetime awaits.
Give yourself some credit. She got there. She got the A levels. I think you could all do with taking a breath and just being relieved the last two years have ended, and with them that level of stress.