I'm Norwegian by the way
Yes true. There are some bigger differances between extreme north and extreme south Europe but still nothing is 100% like you say. Most problematic is central Europe imo. My area alone is so diverse for example. Anyway welcome Norwegian! Well odds of Scandinavian being Slavic are possible. I read onece that to some degree medieval Sweden was settled by Slavic serfs. It was from one Swedish documentary i am not sure how realistic is this and sadly don't remember name but i figure medieval Norway might have brought in some slaves from Slavia i guess.
However most definetly there isn't such thing as Slavic look. I wonder why your friends view u Slavic looking?