“I saw someone.” Depending on who and how you saw the person, we need to use different verbs.
a. I saw my friend. ともだちに あった。
b. I saw my teacher (shopping in a shop but I didn’t talk to her). せんせいを みた or せんせいを みかけた。
c. I saw a doctor (for a consultation). いしゃに いった (literally I went to a doctor) or いしゃに みてもらった (literally, I had my doctor see (check) me).
If you say いしゃに あった, that means you met up with a/your doctor in a different setting, such as seeing the doctor to talk about your loved ones medical condition (but not yourself). いしゃを みた would mean you saw the doctor somewhere but you didn’t talk to him/her.
Also, though not in the picture, I am seeing somebody (a boyfriend or girlfriend) is ～と つきあっています.
