in order to obtain the wave nature of light you need to make your slits as close to each other as you possibly can as well as make the slits as thin as possible.
The two slits/holes need to be VERY close to each other
I applaud you for taking interest in experimental physics! Often times experimental physics is a matter of changing all the variables you have available. In this case change the geometry of the slits :p
I hope this helps. Sometimes we need several different explanations in order for an idea to click. Dont get discouraged! Best wishes! :D
If someone out there can translate this answer to Farsi that would be most excellent and most helpful