I’ve had pushy people before so maybe I’m being too sensitive and she’s not actually being pushy?
I hope @watchkeys sees this sentence because she is very good at this "am i too sensitive" stuff.
OP - why would the fact that you've encountered pushy types before, make you feel that encountering a new one means that YOU are the one somehow in the wrong?
If I'd been run over by a car several times in my life, & this week had yet another incident of being run over - would you expect me to question whether I am "too sensitive" to cars running into me?
What's bizarre is the level of control she is attempting to assert over you. Usually it's more about "but you MUST come out to the bar with me on a schoolnight, I insist!" or "you MUST swap shifts with me because my time is worth more than your time" kind of manipulations from the pushy. All done in order that they gain at your expense.
But your 'friend's' insistences are weird.
To imagine you 'ought' to change the hairdresser you'd consulted, tested with, & booked - on her say-so is beyond pushy OP. It's getting on for reverse-Single White Female territory. And your exam, & your decision on when to sit it, has fuck-all to do with her! What would she know about your subject, curriculum, & readiness? That one is just as weird, & sounds like sabotage, frankly.
Either cut down on the info you give her as PP suggest - Grey Rock - www.e-counseling.com/articles/what-is-the-grey-rock-method/ - & accept that you cannot have a vibrant, interesting conversation or relationship with this friend because she will latch on to your life & try to turn in into hers. This will be boring for you, & also for her, & you will be able to do the slow fade.
OR - ask her WTF she is playing at.
"Sandra, why are you so set in making me change my mind? I am happy with my decisions, it's bewildering that you put so much energy into telling me they are wrong. What's going on with that?"
& see if she is able to perceive her own actions - & from there, acknowledge that they are out of line & amend them ... or if she just doubles down with bluster & justifications.
TL:DR if she can see, & amend, her bossy ways, hurrah.
If she cannot, & focuses on how you are STILL in the wrong, this time for raising the subject of how she is always in the right ... fade her out of your life, because she will bring nothing but frustration & misery to it.