This is the kind of story that I hope to find in a straight to DVD movie OP. If you claim you are new to crypto how can you even consider "investing" 3.000 € only because some Korea girl that you've met trought TINDER told you to do so? What kind of guarantees do you have that this isn't some made up story to exort your hard earned money? Do you think that people create tinder accounts to advertise the secret information that their uncles have and that can make you rich?
are these sites fake sites that try to steal your money ?
I can't find many information regarding oksdaq.com and the few that I did find was some reddit user saying that most of the coins that they offer are a scam[1]. To really know that it's a scam takes very little effort : Just ask both "exchanges" that you intend to withdraw your crypto from their platform and even before doing anything share with us what's their answer. Until we can figure things out I would advise you to stop your investment with them for the moment.
[1] https://www.reddit.com/user/k1ll3rwh4l3/