Hello and welcome to Binky Bunny!
Being siblings does not guarantee that rabbits will bond. If you get one of her siblings now, or any other rabbit, you will have to keep them separated until both have been spayed or neutered, then recuperated from surgery, and allowing time for the hormones to abate. Do you have the room to house 2 rabbits separately for several months? You mentioned getting a female sibling. It’s usually easier to bond a male and female rabbit, neutered and spayed of course, but you can bond same sex rabbits. There are rare times when 2 rabbits won’t bond. It’s due to their personalities. In that case, they would have to be housed separately forever, so you have to be prepared for that, but it’s likely that won’t happen.
If you do get another rabbit and he or she comes from a rescue, he or she will likely be already neutered. That will save you money and some trouble.
Since you aren’t moving for 2 years, I see no reason why you couldn’t get another rabbit soon. You still will have to wait a few months before attempting bonding, of course. Before considering another rabbit, it might be best to wait just a little while. Since you just got your rabbit a few days ago, you need to get used to rabbit care and make sure that you are comfortable with all that goes into their care. Waiting a little while will give your rabbit a chance to grow and get closer to an age where she can be spayed. Most vets like to wait until a rabbit is 6 months old.
Here are 2 good articles on bonding:
https://rabbit.org/faq-bonding-multiple-rabbits/
https://binkybunny.com/BUNNYINFO/tabid/53/CategoryID/9/PID/940/Default.aspx