All you can do is walk behind her in this journey and be there for her if things go wrong. At 18 of course she is finding herself and her uni/career might be put on hold for a while. Isn't that normal for straight and gay and lesbian 18 year olds alike...? She may make decision that you, as her mother and as a person with more life experience, might think and even know are disasterous but the more you try to influence her and push her int he direction you think she should go in the more she is likely to resist that. 18yos are like that, we were all 18 once so I'm sure you can understand what I'm trying to say.

Positive or negative, she'll take the direction she feels is right for her right now. Just follow her, because if things go wrong (IF not WHEN) she'll need you to help her back up (without 'I told you so' ).