Firstly, let me say I think Liam is a great name! I have had two friends called Liam. Think of Liam Neeson?
I hated my male name all my life as it wasn’t the name my mother wanted… it was my bastard father’s name… and he didn’t stick around long either. My mother wanted to call me Stewart so I’ve taken that as my new surname as well as her female line’s middle name. Polly came to me as I would describe my wife as a ‘Polly-Anna’, always being positive etc. So I became Polly in her honour and it suits me as well.
Just go with Liam, dude! Love Polly