Macros, cooldowns and trinkets

[Ualaa]

I'm essentially using the same macro, on my Frost mage.
The spells are the same, but the ordering is a tad different.

I've got Icy Veins, Focus Magic, Presence of Mind, and both trinkets in there.
I have the summon pet, and [pet] Waterbolt in there too.

My pet hasn't died much.
It's more a case of not having it out, after a flight somewhere.
I'm using a Disc priest as healer, on my mixed team, which has the frost mage on it.
So a lot of instant cast Holy Nova spam for heals; can spam it all day, basically.

[Solon]

Not exactly Perrigrin. Instant spells and trinkets are different than spells with casting time. If I understand it correctly myself, your macro gets hung up on casting water elemental when you have no pet and the cooldown is not ready. In that case frostbolt will not get cast until elemental is off cooldown and you have a pet again. The instant spells and trinkets can go after a spell with casting time and still trigger. They don't really follow the order that they are listed in.
So:
/cast frostbolt
/use 13
/cast fireball
should cast frostbolt and use trinket 13, then do nothing until frostbolt or trinket is ready again, fireball will never cast.

/castsequence fireball,
/cast frostbolt
/use 13

should cast fireball, use trinket, cast frostbolt, then hang until fireball is ready again. The fireball line will not advance until fireball is cast again. If you want to have 2 cast time spells on separate lines in one macro you must disable the first one somehow before triggering the second, thus

/cast [nopet] elemental
/cast frostbolt
works great, as long as your pet never dies while the ability is still on cooldown. When you have a pet it ignores the first line and goes to the second.

If you really have that much trouble with macro hanging over casting elemental, then you should move it to a new macro.
Once again, I would move trinkets and instant cast spells after your frostbolt. If you are worried about wasting them on 1 cast trash do this:

/cast [nopet] Summon Water Elemental
/cast [pet] Waterbolt
/cast Frostbolt
/cast [combat] icy veins
/cast [combat] focus magic
/cast [combat] presence of mind
/use 13 [combat]
/use 14 [combat]

If you absolutely NEED them used before your first cast of frostbolt then I can try to come up with something else, but I know it will mean a /click macro for sure.