I empathize with you op. I have found navigating being a parent of young adult DC the trickiest phase. It was so much easier to be a relaxed parent when the stakes were so much lower.
My NT kids (compared to my autistic children) have lived and studied in different cities, travelled widely, clubbed and attended festivals from 16. There were times where my anxiety felt unbearable to me but I never tried to deter them from doing anything they wanted to do as long as it was age appropriate, they'd done their own research and thought through possible issues - transport, contingency and exit strategies etc.
The most they ever knew about my excessive worry was that 'mum likes fairly regular texts so she knows we're still alive'. But importantly, if they ever forgot I was never angry with them or caused a fuss - I didn't want them to burdened by my worry - I just wanted them to see keeping in touch as part of being a responsible adult doing adult stuff.
The other thing I'd say is we all have different levels of tolerance for risk and as parents we all have different childhoods, personal experiences, dispositions, levels of empathy etc and this is bound to affect how we deal with the uncertainties that come with parenting young adults so don't beat yourself up for feeling this way.
I also get a bit fed up with people who are naturally very relaxed/non worriers who dress up their detachment from their kid's lives as a deliberate strategy to promote independence rather than just their own natural inclination to be hands off for an easier life. Even worse when being laid back is framed as some kind of virtue. Sometimes it is, but it can also be a result of a lack of imagination and a rose-tinted belief that nothing bad will ever happen because you were fine at their age. It can also be laziness/ selfishness framed as healthy boundaries - many people seem highly relieved to have got their kid to 18 and consider their job done...