i think the problem that ur having is that your tab is wrong
try hammering from 13th to 15th then bending like this
|-------13b(15)-13-13----------------------------------------
|-----x------------------13h15b(17)b(18)-rb(17)b(15)-------
|---x--------------------------------------------------------
|-x----------------------------------------------------------
|------------------------------------------------------------
|------------------------------------------------------------
i have no problems doing it this way. and it sounds exactly the same as what Gilmour plays. You were never going to do it bending from the 13th fret
I've never performed the solo live but my friend has and i supported him on rythm for a school concert.
David Gilmour ROCKS!!
Ps. try to learn solos and songs by ear thats how i relearnt most of this song after learning it ages ago when i wasnt very good