Does she know you're interested/curious in women?

This is tricky because you already live together and you say you love her. It can go either way.. into a beautiful and blossoming relationship or not, in which either one of you may eventually feel inclined to move out if this rejection becomes too much for you.

I think in this situation, it's best to be honest and accept whatever consequences it may bring.

How? Tell her you missed her while she was gone and see if it sparks further conversation. Tell her she's opened your eyes and willingness to be involved in a romantic relationship with a woman you care about.

She's bisexual and I think will be more open to your curiosity than lesbians typically (but not always) are. From the sounds of it, she may very well be interested in taking this friendship to the next level. You haven't mentioned of any indication she'd not at all be open to it.. and maybe, she's got a crush on you, too.

Step out of your comfort zone and make a change in your life. Whether or not this relationship will work out, it'll teach you something more about yourself. I say go for it. She sounds lovely and supportive. Like you said, if she's not interested, she'll unlikely be harsh about it. I bet she'll be very gentle and empathetic towards your feelings.