Would [name_u]Tristan[/name_u] be a no go if your name was [name_f]Christin[/name_f] 
No, I think thatās far enough apart. Especially since your name is now āMom.ā
I agreeā¦
My youngest calls me [name_f]Christin[/name_f] more than momā¦no idea why :o
I think they are far enough away to be okay. To me too close is something like my name is [name_f]Julia[/name_f] and naming my daughter [name_f]Juliet[/name_f] or my son [name_m]Julian[/name_m].
Funny, my name actually is [name_f]Kristin[/name_f] and yeah, I would never give a son the name [name_u]Tristan[/name_u] even though I like it. My husband and I kind of liked [name_m]Wystan[/name_m] (the poet W.H. [name_u]Auden[/name_u]'s first name) and then it occurred to me that I might have to say the sentence, ā[name_m]Hi[/name_m], Iām [name_f]Kristin[/name_f], and this is my son [name_m]Wystan[/name_m].ā We collapsed into giggles and were like āokay, so letās clearly go with [name_u]Auden[/name_u] instead.ā
I think youāre safe! Anyway, itās not a big problem, and Iām speaking from personal experience - my name is [name_f]Layla[/name_f] and I have a [name_f]Lola[/name_f]! 
My partner is [name_u]Tristan[/name_u] and Iām [name_f]Kate[/name_f], I once joked to him that we could name our children [name_f]Kristen[/name_f] and [name_u]Tate[/name_u] and he said that he actually liked the idea of [name_f]Kristen[/name_f]. This is coming from a man who wants to name a son or daughter [name_u]Tristan[/name_u] though soā¦ Yeah.
I think itās far enough away and they are both well established names, itās not like youāre [name_u]Julie[/name_u] and naming a kid [name_u]July[/name_u] (which is not so well known as an actual name).
I āthirdā @aleerakate. Itās not unheard of for couples to do this, in an honouring way. Think of [name_f]Willow[/name_f] and [name_u]Jaden[/name_u] [name_m]Smith[/name_m], after all! Thatās a more extreme example, but itās definitely doable. [name_f]Christin[/name_f] and [name_u]Tristan[/name_u] are fine, especially because they donāt even look that similar.