Is it a problem if you wore your patch on the fourth week and now you're on the 5th week but your period has not come yet?

Your period will not come until you remove the patch. It is not advisable to do this on a regular basis. Count the 4th week (where you should've removed the patch and didn't) as week one. You are therefore currently on week two. Continue for week three and remove the patch for the fourth week.