I agree with @araminty - it’s more important to use a name that you love, rather than a name that matches your baby’s siblings. What are your other kids’ names? It might help give us a sense of your style and what kind of names you’re looking for 
That said, here are some J names:
[name_f]Julia[/name_f], [name_f]Josephine[/name_f], [name_u]Josie[/name_u], [name_f]Juliet[/name_f]/[name_f]Juliette[/name_f]/[name_f]Julietta[/name_f], [name_f]Juliana[/name_f], [name_u]Julie[/name_u], [name_u]Jules[/name_u], [name_f]Jemma[/name_f], [name_f]Jenna[/name_f], [name_f]Jane[/name_f], [name_u]Jordan[/name_u], [name_f]Jacqueline[/name_f], [name_f]Jade[/name_f], [name_u]Jessie[/name_u], [name_f]Jessica[/name_f], [name_u]June[/name_u], [name_f]Junie[/name_f], [name_f]Juno[/name_f], [name_f]Joy[/name_f], [name_u]Joyce[/name_u], [name_f]Jivanta[/name_f], [name_f]Jerusha[/name_f], [name_u]Jericho[/name_u], [name_f]Jettie[/name_f]/[name_f]Jetta[/name_f], [name_f]Jossie[/name_f], [name_u]Justice[/name_u], [name_f]Justine[/name_f], [name_f]Jasmine[/name_f], [name_u]Jude[/name_u], [name_u]Jameson[/name_u], [name_u]Juniper[/name_u], [name_u]Joss[/name_u], [name_u]Jensen[/name_u], [name_m]Jansen[/name_m], [name_f]Jamila[/name_f]/[name_f]Jamilla[/name_f], [name_f]Joelle[/name_f], [name_u]Jean[/name_u], [name_f]Jeanne[/name_f], [name_u]Joan[/name_u], [name_f]Jessamine[/name_f], [name_f]Jessamy[/name_f], [name_f]Jethra[/name_f], [name_f]Jillian[/name_f], [name_f]Jolene[/name_f], [name_f]Jubilee[/name_f], [name_f]Judy[/name_f], [name_f]Junia[/name_f], [name_f]Julissa[/name_f]