Did you just make Olga believe that you're offering free language exchange to her and now that she caught on, you want her to book a paid lesson?! It would have been better to say openly from the start that you're looking for paying students and not conversation partners.
If someone is looking for a teacher they use the teacher search tool. All these posts on the forum where people look for native English speakers to talk to are in general requests for free language exchange. You might want to check out this post I wrote about the discussion section: https://www.italki.com/discussion/204809. Instead of targeting users who look for language exchange partners, you could start interesting discussions about language learning and correct notebook entries. This way you also catch the attention of potential students.
I can see that you're from Russia, I'm from Serbia so maybe we can check what are our country's similarities and differences? I love to have friendly and open conversations, just let me know if you want to be corrected while speaking or would you like to enjoy and focus on talking?