Nami feels slightly overpowered to me.
She has a surprisingly strong heal for a support with this much cc. It is worth using the heal on an ally even if it doesn't bounce once you hit level 7 or so, and she just turns into some vicious hybrid of soraka sustain and leona lockdown with her E auto into easy-to-land Q + ult combo
In lane she feels very fragile, which is appropriate! I expect she'll get blown up by the aggressive supports if she acts aggressive and destroy the more passive ones.
In teamfights she has plenty to do, especially with all the new activatable items! I never feel goldstarved, even though it's basically impossible to get a last hit with her, but that might also be because i'm getting so many assists/kills. The PBE matchmaking is probably partially to blame, but I think she's also too strong right now.
Additionally I keep expecting her ult to start from right behind her (like the effect maokai's Q has) and I think that would be a fun adjustment!
My suggestions are:
-Make W have a lessened effect on the initial target and a heightened effect on the final target to really encourage the Combat Heal you're going for, as well as reducing her poke outside of a real 2v2 trade
-Make her ultimate start from a tiny bit behind her because it FEELS like a tidal wave should be spawning right on top of her, with a hitbox that extends a ways in all directions at the start
-her E still doesn't look or sound very noticeable. Could it get some sort of marker above the ally's head, like a leblanc sigil or akali mark or something? The actual sound on autoattack with E is great, but my lanemates never realize i've buffed them until a few seconds in.
-Her laugh is less fun now that the water makes a noise! make it quiet again!!