Unfortunately my swedish is not so good (ok, by now I didn't learn anything, too much to do), but I found in the internet, that there will be a ferry, but it starts on the 26th of June.

<Finska RG Line planerar att starta en färjelinje mellan Sundsvall och Vaasa i sommar. Linjen kommer att trafikeras av kombifärjan Kahleberg med plats för c:a 300 passagerare>

<2005 06 26 - 2005 08 06. En tur i veckan mellan Vasa - Sundsvall>

So probably it would be better to go to Turku, if there doesn't exist a bus from Vaasa to your place. I really don't mind travelling, I just want to spend a good time with you :-)
The only problem is going back, because if I have to work on Monday (what I suppose), it's impossible to arrive in Stockholm on Monday morning, so probably hitch-hiking to Vaasa???

Filakia, Jutta