You might try using
http://www.mcmillanrunning.com/
Ignore the goal time and click on "more distances" under recent times. You haven't said how old you are, how recently you've run those times, whether the 5k is on a track or XC, etc. It's really hard to give good advice from the information you've given.
If you're doing a couple hard workouts each week, I wouldn't worry too much about the pace on easy days as long as you don't have significant time constraints like having no more than an hour/day to workout.
Some rough rules I use:
If you're doing tempo work or long intervals (1600m+), use your 5k time in the model (if it's from the track).
If you're doing intervals 800-1200m long with at least 1:1 recovery, then use your 3200m time in the model - however, your 3200 time seems on the slow side compared to both your 5k and 1600 times.
If you're doing repetitions 400-600m with 1:2 work:recovery, then use your 1600m time in the model
If you're doing shorter, faster intervals 200-300m with ~1:00 recovery per 100m run, then use your 800m time in the model.