I used to main Nami and this is my "cycle of maining champions"
1st stage: OMG Nami is so OP, wtf. Heal, CC, auto attack buff, disengage. WTF IS THIS. OMG IM SO GOING TO ABUSE HER FOR FREELO THIS SEASON. I can carry scrubs with her. Why does no one play Nami?!
2nd stage: Well, fuking trash ADCs holding me back. My legendary sushi nami can't carry these noobs lol. Whatever, I bet I'll stop supporting trashes soon enough.
3rd stage: Yep. Told u guys. Nami is literally freelo. Free win. Whatever you call it. I don't see any downsides playing her. YEAH SHE USES MANA THATS A DOWNSIDE INDEED
4th stage: OMG she's so squishy!!!!! Wow I get shit on so hard wtf. Omg her disengage so bad, gets blocked by Braum and Yasuo shield lol. Trash champ. Omgg wow now I know why no one plays her -_- I'm done maining Nami
I think you should try another champion. See, Nami used to be my favourite champion but then I started to lose as her a lot. I started trying new supports, trying to find my own champion. Try J4, another top tier jungler... Sometimes you just gotta get out of your comfort zone (if playing Vi is) and try new stuff!