I think it's very pretty and I do agree it sounds nostalgic and wistful. Maybe in a few years it could join the popular
Penelope? The only nicknames I can think of are Thennie or Thenny (both rhyme with
Jenny) and
Poppy, though that one's a stretch.
masculine list:
https://www.behindthename.com/pnl/191050/124079feminine list:
https://www.behindthename.com/pnl/191050/124080