I can't plant
mine outside where I am either and mine's pretty small right now, too. I just have it in a small pot (~ 4 in.)potted with cacti and succulent
soil. Just water when the soil is dry, and give it plenty of sunshine, and it should be happy.
It's supposed to be a tree
aloe, and will get pretty big if given the room to grow and the right conditions. I think, (but could be wrong) that if you leave it in a smaller pot that it won't get as big as fast.
Hopefully someone will come along and correct me if I'm wrong. There are a lot of people who are WAY more knowledgable than I am....aloes are a new addiction for me.