One question though: how does she not know about what modern swimwear looks like if it has existed since the earlier 1900s? Was she only able to access older books?
The most recent books she has read is from the Sir Arthur Conan Doyle Sherlock Holmes novels. The most recent being "The Poison Belt" 1913. Swimwear from that period of time is quite different from the modern. Just google image search "early 1900s swimwear" then compare those images to the modern day "string bikini" and "speedos".
Also, not too many books that she read discuss or describe swimsuits. Even when it does, reading isn't the same as seeing. Final factor is she grew up on an island where the common garb is sack cloth robes. Her father sometimes wears his full armor, which leaves even less to the imagination.