Boundary question

Hi Brooke, So excited to dive into June. But first … I was doing boundary podcast exercise and this comes up:
I have a 19.5 yr old daughter coming home from freshman year next week. I’m not making much $ right now and have been dipping into savings. I grew up with no money worries, ever, not that we were ultra rich and obsessed with consuming, just that we were really secure, could do what we wanted and never had to think about: if we do this then we can’t do that.
I have this idea that I want my daughter to feel secure and able to do the things she wants within my budget. But I have no budget right now other than my savings.
Before I started thinking about my saying yes to her requests as my boundary issue this happened:
She asked if she could go to Europe with a friend for a few weeks over the summer. They found a cheap flight and would stay in cheap airbnb’s so it’s a really lean budget.
I said yes.
Now I’m looking at this in a boundary context, I want her to feel like she can do things and it will be fine, but it’s not the responsible thing to do for my security.
Do I go back now and say no, you can’t go? (I don’t think they bought the tickets yet which also means it may be getting more expensive).
I’m a little confused around whether to honor my word, and then take this lesson forward in my relationship with her and money, or do I start from this moment and say I made a mistake, you need to get a job and contribute this summer.
As always, multitudes of gratitudes for your generosity and mission!