I need a regular expression to match three different sections of a URL... I think i am close, but there are a couple of small issues and my head is starting to spin!  Any help appreciated:

REQUIREMENT
To split a URL into three parts:

• Category String (may or may not be present)
  
• Product String (may or may not be present)
  
• Query String (may or may not be present)
  

(It should be obvious from the inputs listed which section is which)

INPUTS

 The input is a URL which has the following parts (in this order):

• Fixed String: "/products/" (will always be present)
  
• Category string (may or may not be present): "/cat1/cat2/" OR "/cat1/" OR "/cat1" (notice no trailing slash in last example)
  
• Product string (may or may not be present): "productName.aspx"
• Query string (may or may not be present): "?id=1"
  

 Examples

1. /products/dynamicCategory1/dynamicCategory2/ProductName1.aspx?id=1
2. /products/dynamicCategory1/ProductName1.aspx?id=1
3. /products/dynamicCategory1/ProductName1.aspx
4. /products/dynamicCategory1/
5. /products/dynamicCategory1
   
6. /products/productName.aspx
   

CURRENT REGEX
^/products/(?<categoryString>.*)(?:/(?<productString>.*\.[^?]*)?(?:\?(?<queryString>.*))?)$

ISSUES
This above regular expression works for example 1 - 4 above.  However, I am having trouble getting it to work for examples 5 & 6 aswell

Any help appreciated