Lesbian and TTC (trying to convince)

Hello my fiancé and I have been trying to conceive , but the thing is we are two females and have a donor . I'm honestly still young (20) and don't really understand how to do this all of this like this , I know to wait to be fertile/ovulating . But I just got off the Implanon the beginning of October so my period is pretty irregular , and don't have the funds to buy ovulation test or anything like that . So what I'm asking is does any other fellow lesbians have any advice ? I just have so many questions and no one to help , so please help if you can .