Great that you are enjoying your new saddle. It sounds like you have got to grips with it quite quickly
Don't worry the aches and pains should go away soon and your riding can only improve from sitting correctly and at least your bum should be nice and comfy
I think it could do with going back slightly more...
Not sure about the numnah?
From the EE Website:
What type of numnah or saddle cloth would you recommend?
A16. If using a numnah rather than a saddle cloth, make sure that it is large enough to fit so that the numnah has around an inch at least showing all round the saddle, without any binding seams coming directly underneath the saddle. This could encourage the saddle, with a less than balanced rider, to slip and rub, especially across the back under the cantle region.
The Fhoenix should be always used with a so-called ‘high wither’ cut saddle cloth, such as the excellent Mattes range. All saddle cloths and numnahs should be designed in this way, conforming to the shape of the saddle arch, thereby not pulling across the wither, and creating a pressure point. The high cut also assists with lateral stability, being cut to fit up into the front arch, rather than straight across.
With wide flat backed horses, overweight ones, such as the horse to the right, and those with mature, correctly muscled backs, no padding is necessary. Use only a high wither saddle cloth.
For those with a small amount of atrophy, just needing an extra padding boost, our Backsaver pad,made from the same visco elastic foam as the Fhoenix seat, is ideal, used on top of the Mattes cloth between cloth and saddle.