I was 17 when I had my first BA was a bit of a quick thought and done it within 2 wks of thinking about it! lol!
Mine are still ok and if it wasn’t for me wanting to go bigger I probably wouldn’t be having them done again, however I have had a child since and gravity takes its toll in the end! ha ha!
They shouldn’t go under the armpit hun, you will be fine I’m sure, 10yrs on and I still (on the very odd occasion) get the odd aching day but just look down at what you have and know it was all sooo worth it! xx