3x3 square grid inside ScrollView

Hello, I am trying to build a 3x3 grid with square images (and a label). I am having a hard time because every attempt I make it results in the "squares" being flattened or stretched. That's my code (black.jpg is 200x200):

<?xml version="1.0" encoding="UTF-8"?>
<ContentPage 
    xmlns="http://xamarin.com/schemas/2014/forms" 
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
    x:Class="Milano.MyPage"
    xmlns:src="clr-namespace:Milano;assembly=Milano" >

    <ScrollView Padding="10">
        <Grid RowSpacing="10" ColumnSpacing="10">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="*"/>
                <ColumnDefinition Width="*"/>
                <ColumnDefinition Width="*"/>
            </Grid.ColumnDefinitions>
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto"/>
                <RowDefinition Height="Auto"/>
                <RowDefinition Height="Auto"/>
            </Grid.RowDefinitions>

            <Image  Grid.Row="0" Grid.Column="0" Aspect="Fill" Source="{src:ImageResource Milano.black.jpg}"/>

            <Image  Grid.Row="0" Grid.Column="1" Aspect="Fill" Source="{src:ImageResource Milano.black.jpg}"/>

            <Image  Grid.Row="0" Grid.Column="2" Aspect="Fill" Source="{src:ImageResource Milano.black.jpg}"/>

            <Image  Grid.Row="1" Grid.Column="0" Aspect="Fill" Source="{src:ImageResource Milano.black.jpg}"/>

            <Image  Grid.Row="1" Grid.Column="1" Aspect="Fill" Source="{src:ImageResource Milano.black.jpg}"/>

            <Image  Grid.Row="1" Grid.Column="2" Aspect="Fill" Source="{src:ImageResource Milano.black.jpg}"/>

            <Image  Grid.Row="2" Grid.Column="0" Aspect="Fill" Source="{src:ImageResource Milano.black.jpg}"/>

            <Image  Grid.Row="2" Grid.Column="1" Aspect="Fill" Source="{src:ImageResource Milano.black.jpg}"/>

            <Image  Grid.Row="2" Grid.Column="2" Aspect="Fill" Source="{src:ImageResource Milano.black.jpg}"/>
        </Grid>

    </ScrollView>
</ContentPage>

Those are the result in iPhone 4s:

And iPhone 6 plus:

I even tried with any sort of Aspect for the Images and changing the Height of the RowDefinition from Auto to * but with the same (or worse) results...