Could I break 18?

You have a big aerobic base?

Yeah, you could break an 18. Just start slow for the first half and then explode with all you got in the last 2 minutes.

https://media.giphy.com/media/3rgXBwsbbD6zKG2nkY/giphy.gif

probably not breaking 18 in a week, you're taking a lot of rest during these workouts. however you could definitely improve 30 seconds in a year no doubt. be patient

I think you can break 18 easy with what your long run is. Ending with a 6:30 mile is good. My own opinion is that you are taking a bit of rest in your work outs. If your goal is a faster 5k I would recommend doing more tempo and hill work outs. Go out and find a hilly area and run hard up the hills and relax but don't walk or jog on the downhills. I start at 15 mins of this and then I increase my minutes bi-weekly. My max is currently 25. Do this after a good 10 minute warm up and do a good 15-20 minute cool down with this workout as well.