Do slightly lower senior year grades significantly impact decisions?

Hi all! I’ve recently applied to several prestigious schools, namely Columbia, Pomona and Brown. My GPA has always been strong with almost all IB/AP classes (97.2 average unweighted, 99 weighted for first three years of high school). I also have very strong SAT scores, extracurriculars, essays, etc. Assuming my chances were possible at these top schools before, how much will a small dip my senior year impact decisions? I got my first B in all of high school (89 in physics) in quarter 1 of senior year, along with a 92 in gym, (I usually had a 98+ in both classes) because I’ve been very depressed and have had difficulty keeping track of due dates and concentrating (I forgot my gym clothes a few times and missed some physics homeworks), but my overall GPA in quarter 1 was still a 95 unweighted. Now, as quarter 2 is coming to a close, it looks like my grades may sink again (I’m aiming for about a 94 average unweighted, but worst case scenario maybe a 92 with several high-Bs/80s). I have been speaking to a therapist about the possibility of having ADHD and/or depression, but I haven’t received any sort of diagnosis, although my therapist believes I definitely have a clinical issue. Should I look to find some sort of diagnosis so as to alert my colleges, or would that do more harm than good? I understand these grades are by no means the end of the world… I just do not want to jeopardize my chances all because I look like I’m in a senior slump. Thank you for reading in advance!