Egi pathWhich... I mean... I'm not all that up on my SMN lore, I gotta admit, but I'm somewhat under the impression that a major, unavoidable part of being able to summon egis (i.e. personifications of elemental magic) "safely" (i.e. without undergoing what would essentially amount to just a primal summoning ritual...) was having been present at the defeat of the corresponding primal in the past, allowing you to "bathe in their aether" at the moment of their demise.

Sidestepping this limitation seems like it could have major issues if you ever try to RP your character with another character who is a Summoner - since you'd essentially be suggesting that the hard work and danger that character went through was meaningless.

It sounds like your character is something of a pariah from what would normally be her support network, yes? And she imprinted the roles of friends/family upon the elements she was able to manipulate, personifying them? How strong is her attachment to the idea of these personified elements?

Would she be lonely enough (and therefore dedicated enough) to, say, go through the hassle of making contact with the Sons of Saint Coinach, the danger of signing up to fight manifestations of Ifrit or Garuda, and the hard work of subsequently obtaining a soul stone and becoming A Summoner (capital job title letters) - in order to achieve her goal of giving form to these elemental companions? (Bear in mind she must either have the Echo (completely possible), make stringent and expensive preparations (supported by fanon if not canon), or be really lucky in order to avoid tempering at the hands of either of these primals.)

Carbuncle pathOr - as an alternative - could these simply be personalities/traits that she impresses onto certain custom geometries of carbuncle? Because I don't know how far along the "average person <-> hero of Eorzea" scale you're aiming for, but if it's closer to the average person end, then that's an option.

Creating custom geometries seems to involve a large amount of study and just flat out intelligence, as well as contacting other scholars to troubleshoot and receive input on the direction and purpose of the geometry, but if your character has been a hard-line student of arcanima for years then this might not pose so much of a problem. It certainly doesn't require any "super-human" traits like killing a Primal does.

Voidsent pathOf course, there's always the "darker" option - that she thinks she's given her friends sentience, but actually what she's done is welcomed voidsent (probably imps, possibly succubi or dullahan... etc) to occupy whatever forms it is she's created for them. She remains unaware of this until much later. There's plenty of examples citable of lonely, determined, powerful people trying to solve problems for themselves and ending up summoning a voidsent instead. But that puts a completely different spin on the storyline for your character and may not be what you want.

Mammet pathLast alternative I'll suggest because I think it's cute - mammets. Mammet hearts lend rudimentary sentience to mechanical creatures like, well, mammets, but also larger magitek chassis, and fanon has them providing similar services at the core of various cyborgs, puppets, and marionettes. Could becoming a mammeteer (rather than a summoner) be something closer to what your character would wish to achieve?

...I have to admit, the idea of a sentient wind-up Ifrit or Garuda is really, really cute. xD I mean, have you seen how fluffy the wind-up Garuda is? It's so fluffy.

...anyway.