Has she told you she needs help with this? Only asking because if she isn't actually telling you that she needs to see a councellor, because her feelings are distressing to her, then she might well actually be telling you that she is probably gay, but doing it gently (drip feed style to let you..and her, get your collective heads round it) and she may simply need a 'that's absolutely fine darling, I adore you and will be as happy to see you with a girlfriend as a boyfriend'
The 'I'll love her no matter what' suggests that you DO find it a little difficult..and that is fine and understandable because no matter how open minded we all think we are, it is always odd when the goalposts have just shifted a little!
My eldest (of 4.. wow you have 8?!?!) is 22, and came out as gay two years ago. She had known for sure since she was about 15, but wanted the 'normal' (her words) and tried to have boyfriends. She knew we couldn't give a monkeys about our childrens' sexuality as long as they were in happy loving relationships, but she STILL found it hard to tell us.
When she did it was the biggest non event ever.. evryone from her Dad to her Grandma went ' cool, ok now go find a girlfriend and be happy' (oh and when she brought home a girlfriend her DB1 said ' It's not fair..how come SHE gets the hot chicks
) and now two years on she IS happy. Incidentally it was at Uni she found her feet..and courage, and is part of a brilliant , supportive, wonderful bunch of Lesbian, Gay friends who are frankly some of the best young people I have ever met :)
I honestly had no idea.. because she couldn't be less like the stereotype that I imagined (she's more Portia de Rossi than Ellen de generes looks wise!) and to my shame I had preconceived notions!
I don't think you need to DO anything, except make it clear that it's no big deal (to you..obviously it is to her!) and that she is wonderful.
My hunch would be that she may well be gay because by 18 i think most have an idea one way or another:)
It took me about a day to go from 'oh ..oh wow' with my visions of her married to a handsome doctor (she's a medical student) disappearing, to ' well she can still have babies with IVF or a turkey baster' (she wants children) to.. ' I am very proud of having a gay daughter.. sock it to them!'
:)