Dad related sexuality to PSSD

So my dad tried to relate my sexuality of being gay to PSSD, which is post-SSRI sexual dysfunction, because when I came out I said "I'm not attracted to women" but didn't say "I was attracted to guys" even though I said "I'm gay" and that's what that means? He also said "if sometime in the future I'm not sure if I'm gay and this is related" we could talk about it. And I don't understand why he is doubting me just because he read some shit on an anti-depressant side effects page and I literally don't have the symptoms of PSSD. For clarification I came out to my parents this past weekend and they didn't have a problem with it but also didn't have any questions, and now they do have questions but don't want to ask unless it's in person and my Dad said my mom won't bring it up unless I do cause she doesn't want me to feel embarrassed. Also another clairificarion- I'm on Lexapro generic and I'm in the process of switching doctors cause I believe I am on too much and now that I'm not hiding my sexuality I feel way way better and this doctor just isn't working with me. Any input/suggestions?