you don't really need a separate table for each product type
Take size for instance.
In a simple two table relationship, your tables could be like this…
On your products detail page, (filtered by your URL parameter), the size options available in your dropdown list could be obtained as follows…
SELECT SizeID, SizeDescription FROM sizes WHERE product ID = x (where x is your URL parameter)
So, if t shirt is productID 1 and dress is productID 2
Sizes table would be like this..
Size ID ProductID SizeDescription
1 1 small
2 1 medium
3 1 large
4 1 x large
5 2 size 4
6 2 size 6
7 2 size 8