You may be able to go from a tourist visa to a bridging visa, then onto a fiancee or spousal visa, however they can just as easily kick you out for coming here on a tourist visa under false pretences.

The right way to do it is to apply for a visa wherever you are and wait for approval. This is what my husband and I did and he got his visa through without too many problems. You need to prove that you have a true ongoing relationship and your sponsor may need to support you. This may be a problem if she is still in school.

Your other way to do this may be to look under the skilled migration avenue. Or find an employer who will sponsor you.