Bryony is gorgeous, such an underused name. I know one who goes by Bree (she's 17)
Anyway on to your name list..
Merryn - I love Merryn, it has such a happy feel to it. It also has the known but underused and a bit different vibe that Bryony has
Olivia - I love Olive, but find Olivia a bit Meh. I think it's because it feels a bit overdone as I hear it all the time
Astrid - I like it, though known 3 Astrid's who are under 1 so it seems to be having a bit of a moment atm which personally makes me avoid names
Phillipa (Nn Pip) - Phillippa I love! Also love Pip and Pippa though to a lesser degree. Goes lovely with Bryony too
Alex is - not a fan
Freya - I like but it's very popular in my area
Helena - I like but only the Helen-uh pronunciation so would avoid personally
Eleanor (Nn Nel) - I like but worry it would be naturally shortened to Ellie. I really like Nell though, and Ella. I personally prefer Eleanora nn Nora
I would go for even Bryony and Merryn or Bryony and Phillippa. Both are gorgeous and go really lovely together