We would need more context (especially the text before your quotation) to be sure. But my preliminary reading would indeed be that she felt it was not "up to her" to do it. Needless to say, the expression would not be written this way in classical Latin.
Aliquot as an indefinite adjective is common and is very suitable for your purpose.
Here are some examples taken from archaic and classical authors:
Cato, orig. fr. 128 Peter: interim aliquot <p>au<ca> castra feci
Plaut. capt. 161: eorum sunt aliquot genera Pistorensium
Cic. Cluent. 168: dico illum [...] aliquot dies aegrotasse et ita
Searching "aliquot castra" I happen by luck to find an old article (Rand, Edward Kennard. "On a Passage in Virgil's First Eclogue." The Classical Journal 2.3 (1907): 125-128.). in which the issue at hand is mentioned (tersely unfortunately).
In that paper a passage from the Ecoluge is dealt. For our need however, the relevant line is: