Android layerlist is not working in different mobiles

I want to create a drawable file like the below screenshot.

My drawable xml file:

    <layer-list
        xmlns:android="http://schemas.android.com/apk/res/android">
        <item
            android:drawable="@drawable/green_button"/>

        <item android:left="@dimen/_11sdp"
            android:gravity="center_vertical|left"
            android:drawable="@drawable/radio_button_bg"/>

    </layer-list>

    //drawable/radio_button_bg
    <?xml version="1.0" encoding="utf-8"?>
    <selector xmlns:android="http://schemas.android.com/apk/res/android">
        <item >
            <shape android:shape="oval"  >
                <solid android:color="@color/darkgrey">
                </solid>
                <size android:width="@dimen/_15sdp"
                    android:height="@dimen/_15sdp"/>
            </shape>
        </item>
    </selector>

    //drawable/green_button
    <selector xmlns:android="http://schemas.android.com/apk/res/android">
        <item >
            <shape android:shape="rectangle"  >
                <corners android:radius="6dip" />
                <solid android:color="@color/selected_slot">
                </solid>
                <!--<stroke android:width="1dip" android:color="#5e7974" />-->
            </shape>
        </item>
    </selector>

I created two separate files and I merged them by using layer_list. But the issue is it is not working in different mobiles, also the white circle inside the drawable is becomes big after setting height and width.

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