I agree that perhaps not enough comfort after sex and texting a few days later saying wanna meet up again implies you just want to get laid again.
A better way would have been to text her the next day with something harmless like a funny GIF or just positive normal conversation. It takes attention away from any possible sexual complexity.
Also if she is going to europe she is not going to invest much towards a LTR so you have to position yourself somewhere between a ONS and a LTR if you want to see her again. That's not always easy but if you want her as a summer girlfriend you may have to communicate that at some point. I wouldn't neccessarily give up. Text her again but don't put any pressure on it. Just send some harmless fun stuff that makes her day. Women are moody, if you keep in touch she might be more responsive when she's in a better mood.