Align items in a RecyclerView at the bottom

I have a RecyclerView inside of a ConstraintLayout whose top starts at the bottom of a textView, and whose bottom stretches down to the parent. I want the items in this RecyclerView to default to the bottom of the RecyclerView. I tried adding gravity="bottom" and also tried the same thing with foregroundGravity and layout_gravity. I also tried adding layout_gravity="bottom" to my recyclerView item's layout. Still, all the items in the recyclerView continues to default to the top. Is there anything i can do to make sure the items are at the bottom? Here is the xml:

<android.support.constraint.ConstraintLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/my_tv"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:text="needed to unlock next coupon"
        android:textColor="@color/gray"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/irrelevant_tv"
        android:layout_marginTop="@dimen/spacing_tiny"
        android:gravity="center"
        />

    <android.support.v7.widget.RecyclerView
        android:id="@+id/rv"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginTop="@dimen/spacing_xl"
        android:paddingTop="@dimen/spacing_large"
        android:overScrollMode="always"
        app:layoutManager="android.support.v7.widget.LinearLayoutManager"
        app:layout_constraintTop_toBottomOf="@id/my_tv"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

</android.support.constraint.ConstraintLayout>

I don't want to do wrap_content on recyclerView either, because otherwise it is not scrollable (I always have 3 items in this recyclerView, and based on the user's display settings, the recyclerView can get pushed off the screen, which requires me to be able to scroll)