Pearl is lovely. Here are some names that may work.
Roses are the 'birth flower' associated with June. You could go with a Rose variant.
Pearl Aurora is classically beautiful and evokes Summer! I LOVE Pearl Seraphina! It was on my list but DH has now vetoed it as a choice :( I really love suggestion of Pearl Rosalie too... Stunning! Pearl Susannah is gorgeous too! Susannah always reminds me of Summer and you could even use sunny as a fun nn!