With your speed, you've got lots of room to improve. I ran close to 16 minutes (I'm a guy) with a slower 100m time.
Things to consider:
1. Never smoke another cig. This is a no brainer.
The rest of my thoughts are entirely overriding principle that you listen to your body and adjust as necessary:
2. Slowly build the mileage up. 45 mpw is not very high, especially if you were only there for a short period of time. Try to get to the point where 45 is an easy week, and you're at 55 most weeks.
3. Don't push the easy runs. Let the pace come to you. You'll probably find some days are super slow (you may find yourself running 10 minute miles the day after a hard workout). Other days you'll feel great and may end up easing into sub-8:00 pace by the end.
4. Focus the hard efforts on 4 types of workouts (maybe 2 per week or 3 if you're feeling great...since you are young, you probably recover faster than old guys like me):
a. Threshold effort runs: I like to mix it up, some days straight tempo for 20ish minutes, other days repeat 1000-2000m with short recovery.
b. Steady runs: For you, 7-8 miles is probably reasonable. Ease into the first mile or 2. Run the remainder around current 5k pace+1:00/mile.
c. Date pace->goal pace intervals: I like interval workouts where you start with longer reps at your current date 5k pace and finish with shorter stuff at goal pace. An example for you might be something like 1600m 7:15, 2x1200m 5:15, 3x800m 3:20, 4x400m 95 with 400m jog between everything. I probably would drop the volume the first few times you do this (maybe only 1 1200m, 2 800s, 2 400s or something).
d. Easy fartlek runs with some short hill sprints and striders (full recovery, nothing lasting over 20 seconds or so).
Above all, learn to be in tune with your body and don't be a slave to a schedule.