Increased turnover is not the key.
Why wait to OP's 3rd year of college before he can have the success he wants.
OP will get very good results working on his speed, and in a couple of months he can post.
His 2:14 and 4:55 are fine times. Especially on the same day.
I could have broken 16 for 5K at the end of my HS soph year in track. We didn't run 5ks.
CC my junior year was 3 miles. I got pushed from behind in the chute at the CC sectional meet, 8th place on a hilly course, and landed awkwardly on my fully extended leg (no flex to absorb the shock). I ran the state CC meet while having to take short strides with no power because of the injury to my lateral-collateral. My coach was massaging my sciatic nerve in the team box at the start before the state championship race, in the hope that I could run at all. Therefore, on a rainy day with mud patches on the course, I still ran just over 5 min a mile, The wet ground, and especially the mud patches, strained my swollen lateral-collateral, so I had to run gingerly while trying to run as fast as I could. My time translates easily to a sub 16 minutes for a 5K. This is a well-known CC course for the state meet, and not some "fast" CC course. If not injured, I would have raced with the runners that I normally finished around, and on this slow day those guys averaged 4:53-4:55 a mile, and that projects to about 15:20 for 5K.
Maybe my running with short strides and not much push is how slower runners normally run...I don't know.
As a senior in HS, I was expected to finish 1st or 2nd in the state for CC. On a dry, decent day, I was expected to break 14 minutes, which is sub 14:35 for 5K.
These times occur while in HS, not waiting until my 20s.
No sports my senior year. Before the start of the HS CC season, I jumped into a 4 mile road race (ran 20:04). A few weeks later, I ran a 10K held on a golf course in 32:33.
That same fall, I won the AAU CC Junior Olympic district meet on the hardest course in the state (3 miles), and had a wood chip catch on my spike for the last mile (thought I was going to damage my knee, and I couldn't take of the shoe and run barefoot because of all the wood chips that might cut my foot, and other impediments). Even though I had to float the last mile, I still ran one of the fast times that had ever been run there, and others who ran near my time raced in the low-to-mid 14s for 3-miles in the state CC meet. I also got 4th in the regional AAU CC Junior Olympics, held in another state after leading the entire race until the last 400 (too many flags and sharp turns at the end, it was like running in a maze).
[The only runner who could have challenged me for CC that year--if we had sports--ran just under 14:10 in the state meet, but that was because it was a freezing cold day, and I could not hoped run much faster, and maybe around the same time, under such cold conditions.]
The focus on mileage may work well for some, especially in their 20s or older, but OP is 17.
By working on his speed, OP may break 15:33 for a 5K within a year, after he gets much faster, .
He will get much faster if he pursues the interval workouts with the suggested way of taking long, powerful strides by leaping forward while maintaining momentum.