Are you marking your Products as either:
Product is Virtual: Yes, Skip Shipping Address
Always Free Shipping: Yes, Always Free Shipping
Or as 0 weight where 0 weight is setup in the Configuration ... Shipping/Packaging ... as Free Shipping:
Order Free Shipping 0 Weight Status
If there is no weight to the order, does the order have Free Shipping?
0= no
1= yes

Note: When using Free Shipping, Enable the Free Shipping Module this will only show when shipping is free.
or using the Modules ... Order Total ... Shipping ot_shipping and setting Free Shipping on orders over some amount?