What training did you do during summer before your freshman year? 25-30mpw? Or was that in season only?
Your 11:30 two mile time suggests a 5k equivalent of 18:25ish.
Your 5:07 mile time suggests a 5k equivalent of 17:34ish.
Assuming you haven't lost too much since track ended (a month ago?) then you can probably already break 18 min.
If you were just running 15-20 mpw in track then you've got a long buildup to get to 45-50 mpw. Have you been running since track ended? Hopefully you have.
I would start by shooting for 30 mpw for now over a 6 day week if you have been running since track ended. Take one day off a week. A little rest can help prevent injury and keep you fresh. So 30 miles per week is 5 per day average over 6 days. Knock a couple of those runs down to 4 miles and then do a long run of 7 miles once a week.
After a couple weeks bump it up to 33 per week and maybe start adding a tempo run once a week on a pretty flat route - perhaps 25 minute run at 6:25 pace. If you can do that relatively comfortably then you're probably in sub 18:30 shape now. If it takes an all out effort or close to it then you've lost a little since track and should maybe back off the 6:25 pace.
Don't make the mistake of running a fast first mile during the tempo run. The goal is to maintain the 6:25 pace throughout. Not go 6 flat and then struggle to run under 7 min per mile the rest of the way in. If anything, you should be able to bump up the pace to 6:15 or faster at anytime during the final miles of tempo run if you had to (but that's not the goal here). If you fall off the 6:25 pace dramatically, you'll need to readjust to a slower tempo pace for the next run.
It's better to run the first mile slower than goal pace (maybe 6:30-6:35) and then speed up a bit. I use a GPS watch and set the auto lap for every 1/2 mile.
Keep the same route for your tempo run and vary it by occasionally going for 30 minutes at 6:28 pace or 20 minutes at 6:20 pace (assuming that the first tempo run goal was accomplished with quite a bit less than an all out effort).
After three weeks, you can consider bumping your mileage a bit each week but (depending on what you've been doing since track ended), I don't think you'll get to 45-50 miles per week before season starts (mid August?).
If you can get in 4-6 tempo runs before the season starts, I think that is plenty. Don't worry about intervals, fartleks, hill repeats until the season starts. You'll do plenty of that in season - no sense peaking on August 15 and going downhill from there.
The tempo runs of 20-30 minutes will give you a lot of confidence going into an 18-19 minute race. You'll know that you have trained to run longer than that at a challenging pace so the 5k should seem less daunting. Take what you've learned from the tempo runs and apply to the 5k races.