I can relate to your weed problem.i had ton of weeds in my yard and this last year I think I have them in check.first thing I see you used round up.well make sure you use it when the temps are above 60 degrees.first thing make sure you put down pre emergent spring and fall.i use stonewall because it's the easiest to use its simple spilt yearly amount into 2 applications.what kind of grass do you have.now after you do the pre emergent you can spot spray weeds with different weed killers.caution if you have Bermuda don't use round up when grass is green.only when Bermuda is dormant.
Spot spray- but key to that go on n.c.state university turf files and search what weeds you have-it will show pic on weeds and also description of weed .the below that what chemical to spray etc.
Now do the weed that is most dominant and keep doing them in order that grows.
Important do the weeds when they are actively growing first.and do pre emer for a couple years and then you can kiss weeds goodbye.