how do i tell my mom i don’t want her at my doctors appointment?

recently i had a super traumatizing colposcopy done where my doctor found 2 lesions on my cervix so they scheduled me a follow up appointment to discuss another procedure and treatment i guess? when the nurse called me with my results she sounded as if she had just read them for the first time…it was a lot of pauses and ummmms. she told me “it’s not cancer but it’s not not cancer” when i asked if the results showed i had precancerous cells. my appointment was scheduled for may 21st at 10 am but at 9:30 they called and cancelled. my mom knew i had this appointment since it was scheduled almost 2 months ago but since then we are not on good terms and i’ve hardly spoken to her. when they cancelled my appointment they rescheduled me for the 31st of may and then i just went to work. when i got to work i saw my mom had texted me at 10 asking if i was at the doctors office and then another text saying they told her my appointment was cancelled and told her the day/time they rescheduled it to. first of all i wasn’t even expecting my mom to be there since it’s a 35 minute drive and she works. when i asked why she was there she said “to comfort you and be a second pair of ears.” how do i tell her in the most appreciative way that i do not want her there. yes i appreciate her wanting to comfort me and missing work to do that because yes this whole process has been traumatizing and i’m definitely scared on what their plans are procedure/treatment wise but also i’m 23 and this is my gyno history that i don’t want my mom hearing about? and also just to catch me off guard like that…we haven’t talked…so if i would have had my original appointment and she just showed up expecting to sit in the room with me i would have had to just say yes to not cause a scene and to not make her upset. it also makes me even more upset that my gyno office broke hippa by telling her my new appointment day/time so i called their office the next to day to confirm i never listed anyone they could talk to about my info…what’s even crazier is my mom said she never gave the receptionist her name, just said she was my mom. all the office manager did was agree that the receptionist shouldn’t have given my info out and offered to reschedule my appointment…another month out. so i’m keeping the appointment on the 31st but how do i tell my mom to not come and not sound ungrateful or whatever. my mom is definitely the “i guess i’m just the worst mom in the world” type and her saying that drives me insane because she’s not a bad mom and i do love her and appreciate her but for my own mental sanity i can not be around her or talk to her due to things that have been happening for the past couple of years.