You are !
Well done Susan. Nicely done. and your friend with the wheelchair. Wow.
Oh and I won't run much the next 7 days, upto 2 weeks so that's my less is more bit. 5-10 miles maybe. This week is most I've run ever in 7 days so rest needed!
Ikle, backing up what Fido says, you don't need to force that long run pace... You could just end up knackered or injured.
For me.. "training" pace in long runs over say 14 miles is 45-90 seconds slower than your target so 9:45-10:15+ is fine for you... That's the way I always do it. I did 9:15-30 last year for first 20 miler when going for sub 3:30 (which is 8 min miles).
Then gradually get tighter on that range nearer the race but never big chunks, or the whole run. Most I would do is 1-5 miles at end and only if I felt up to it. Even the last mile at MP is enough. Just doing 20 miles is tough enough.
Can do the 9:00 ish pace on your midweek medium run. Any speed work much faster 7-8 min mile pace.
Once you taper, you'll get more endurance than normal and fingers crossed get that time.