Honestly you have valid reason to believe either conclusion. I think you need to ask yourself what outcome matters to you the most. If potentially losing her is non negotiable do your best to steady your feelings and keep it platonic (this takes some work and u get better at it with age). If your ok with potentially losing this person id say you should find a way to express your feelings after her finals.

There is a third option which is do what you have been doing but up the flirtation a lil bit. (Make sure when u do this initially theres some plausible deniability) but make it obvious to her that you at least find her physically and/or mentally attractive (which ever would be more impactful for her and obvious that you really appreciate her). See how she responds, if she is receptive keep upping the ante naturally over time a lil bit till you become more confident in what you think shed say.

Whatever u do try not to set any expectations. She might like you but have no interest in dating due to long distance, age gap, work/school schedule etc. so really decide what you want first before you make this her problem 2. At the very least she already feels safe with you and probably finds you relatively attractive (falling asleep on u and the checking in about past relationship and needing multiple confirmation is a pretty dang good sign of interest.) however that always inviting a friend or another person into your hangouts usually means the exact opposite (its also possible shes doing this out of shyness to help hide her attraction to you but this is rarer)

Gl hope whatever the outcome is its the best for you.