I noticed that bonpatron.com offers the following option: "je est féminin" and goes on to say "Cette option contrôle si BonPatron doit interpréter la première personne du singulier («je») au féminin; ex: Hier, je suis allée au cinéma." I would like to understand how this rule of grammar works. My googling skills are not great, I tried "french grammar je feminine form/conjugation" and have turned up nothing. Could someone direct me to a page that will break down this concept, its rules and any exceptions, and/or explain it it? Thank you!
One may interpret je as being one of two possible words with the same spelling, where one je, the masculine, is the first person version of the third person il, and the other je, the feminine, is the first person version of the third person elle.
If one identifies as female then she would use je suis allée..., in comparison to a male saying je suis allé.... This is also applicable to all the other pronouns whose spellings are gender-independent, such as tu, nous and vous. For example, if one is talking to a group of women, then they might say vous êtes allées... rather than the vous êtes allés... that they would say, if at least one of the group were male.
The only agreement you will have to do is to use the adjective's feminine form, and some nouns feminine forms as well, when you use a verb that belongs to the few verbs called verbes d'état (être, devenir, paraître, sembler, demeurer, rester, avoir l'air). Those verbs express the state of their subjects, that's why they are followed by an adjective or a noun that has to agree with the gender (and the number, i.e. singulier/pluriel) of the subject. (note that this applies for all verb tenses)
fem: "je suis grande" / masc: "je suis grand"
fem: "je deviendrai une personne célèbre" / masc: "je deviendrai une personne célèbre" (the word personne is always feminine)
fem: "j'ai l'air idiote" / masc: "j'ai l'air idiot"
fem: "j'étais collaboratrice" / masc: "j'étais collaborateur"
For the verb conjugation at passé composé, only some verbs require that you pay attention to the gender of the subject. Those verbs have in common that you form the passé composé with the auxiliary verbs être instead of avoir. Those include some movement verbs:
aller, monter, partir, etc... :
fem: "je suis allée/montée/partie" / masc: "je suis allé/monté/parti")
and all reflexive verbs:
se mettre, s'asseoir, se développer, etc...:
fem: "je me suis mise/assise/développée" / masc: "je me suis mis/assis/développé"