First Deep Clean-what to expect?

Hi guys, for context i’m 23 and haven’t been to a dentist in about 12 years, due to some insurance struggles growing up. in more recent years, about 5 or so, i started really struggling with my mental to the point where getting out of bed was hard let alone take care of my teeth.

i had experience with the numbing shots along the gum line when the navy took my wisdom teeth, but i was also scared shitless and i think i just froze instead of being mentally there for the procedure. (i was awake when they took my teeth, horrible experience i remember the smell of my bone when they were slicing one in half to get it out)

i had my first exam yesterday, which consisted of x-rays and 3d scans of my mouth. turns out, i have 20 cavities and plaque has been building up under my gums because it’s been so long. my deep cleanings are scheduled in april and they’re splitting it into two separate sessions for each half of my mouth. my cavities aren’t bad enough for root canals, which i’m grateful for.

my front gums are pretty bad- the puffy inflammation and all that. i guess what i want to know is, will it be painful at all? since my gums are already inflamed will getting the shots hurt more than usual? i know ill probably feel them scraping up in there, but is it a painful sensation or more of just pressure/discomfort? what does the aftercare look like for it? idk im just really nervous and scared of the pain more than anything and i know that this is just the first step in my journey, the navy dentists really messed me up because they did not care at all or communicate anything that they were doing and i just want to come in with a clearer idea

anyways, thanks for reading and your time. sorry for the barrage of questions im just nervy.