Toolbar Image Issues

I am trying to use the toolbar items in Xamarin.Forms. However, I am having 2 issues that I am not able to fix.
1. I am not able to center the logo of the app in the middle of the toolbar.
2. The logo image looks fine on IOS but is shrunk on Android.
How do I do these things in Xamarin.Forms? These seem like simple things and I feel like there might be something I am missing.

Here is the code I am using.

<br /> &lt;ContentPage.ToolbarItems><br /> <ToolbarItem Icon ="logo.png" Priority="0" /><br /> <ToolbarItem Text =" " Priority="1" /><br /> &lt;/ContentPage.ToolbarItems><br />