Split delimited string in SQL Server

I have the following slash-delimited example strings and need to split them:

Record---String
1--------ABC
2--------DEF/123
3--------GHI/456/XYZ

The strings will always have 1 - 3 parts; no more, no less.

To split them I have been using this function:

CREATE FUNCTION [dbo].[Split] (
@chunk VARCHAR(4000)
,@delimiter CHAR(1)
,@index INT
)
RETURNS VARCHAR(1000)
AS
BEGIN
DECLARE @curIndex INT = 0
    ,@pos INT = 1
    ,@prevPos INT = 0
    ,@result VARCHAR(1000)

WHILE @pos > 0
BEGIN
    SET @pos = CHARINDEX(@delimiter, @chunk, @prevPos);

    IF (@pos > 0)
    BEGIN -- Characters between position and previous position
        SET @result = SUBSTRING(@chunk, @prevPos, @pos - @prevPos)
    END
    ELSE
    BEGIN -- Last Delim
        SET @result = SUBSTRING(@chunk, @prevPos, LEN(@chunk))
    END

    IF (@index = @curIndex)
    BEGIN
        RETURN @result
    END

    SET @prevPos = @pos + 1
    SET @curIndex = @curIndex + 1;
END

RETURN '' -- Else Empty
END

To split the strings, I call this function like so:

MyField1 = dbo.Split(MyInputString, '/', 0),
MyField2 = dbo.Split(MyInputString, '/', 1),
MyField3 = dbo.Split(MyInputString, '/', 2)

The expected results would be

Record 1:
   MyField1 = ABC
   MyField2 = NULL
   MyField3 = NULL
Record 2:
   MyField1 = DEF
   MyField2 = 123
   MyField3 = NULL
Record 3:
   MyField1 = GHI
   MyField2 = 456
   MyField3 = XYZ

It is almost doing what I had hoped, except the last character of MyField1 for Record 1 is being truncated resulting in "AB" instead of "ABC". I believe this is because there is no slash delimiter for this one-part string.

Unfortunately, I did not write this function and my SQL skills are a bit weak. What should I change to make this function return proper results when there is no delimiter in the string?