I'm not too sure of access to online speech therapy in your country but it's common here in the UK. You could check out the ASLTIP website which is association of speech therapist in independent practice in the UK and filter to adults, stammering and online and see if any therapists are available and would work with clients abroad. I'm not sure due to licensing whether they'd be able to but worth a check. Many will offer a short free intro call. You could also search for the Polish or Spanish equivalent but I'd assume the therapy would be in those languages. There is an app called 'Benetalk' which was developed by people who stammer which shares information about stammering and also some strategies to try. It's not a replacement for actual speech therapy but again might be worth giving a go in the meantime. Does your university have a student support services department, and have you requested reasonable adjustments for your stammer? This might help. https://stamma.org/get-help/work-job-hunting/reasonable-adjustments-stammering