You might have good coach already now, but somehow the first serve is not improving.
Then its good to send it here, a video clip of like 3 serves, pref in slomo.
You might get excellent advice here as quite a few people here have very good knowledge about technique, incl Ash. You just need to filter it, as some ignorants try to post advice also.
On another note.... 110 m/hour...that what some top ATP players do during a match, like #5 David Ferrer. Placement, spin, variation are all very important....and there are more factors related to holding serve, like recovery, the second ball, and your overall competence.