Easy pace sounds about right to me. But if you are very tired, maybe consider -
- Did you recently increase mileage? Possibly a bit too much too soon?
- Could you benefit from a down week? Have you done one in a while?
- Is your long run at a slightly slower pace than your easy runs? Advanced runners will have faster paces for all or part of their weekly long runs, but imo probably not the most productive for 17-18 min runners. I'm not an expert but I believe this is correct.
- Is your long run overly long for current fitness? Have you increased it too much too soon recently?
- Is your tempo run at the right pace, or are you pushing it too hard?
- Is your tempo run possibly too long for your current fitness?
- Are you hammering your interval session too hard?
- Are you possibly running too many extra miles before/after your tempo/interval sessions? Some runners will benefit from the extra easy mileage, some are just wearing themselves out with unhelpful slow jogging/slogging. Depends on you, and your current fitness.
- Too many strides during the week? With 3 hard sessions, at your level (17-18 min) you could probably just do a few short sprints after the tempo session.
- Do you have 1 day off per week? As a 17-18 min runner, I'd suggest that this would yield better results than one more day of running, given that you have 3 hard days per week. Remember that rest/recovery is part of training.
- Could you benefit from converting 1 easy day to a cross-training day, say maybe alternating bike / pool / elliptical / whatever? Some runners will actually do better with this, because the running-specific movement gets a break but you are still getting basic cardiovascular training.
- Are you also lifting? That can be tough with 3 hard sessions, but it may be ok if you keep leg days away from easy run days and off days.
Just some thoughts, hope this helps.