boyfriend talk/ trying to get pregnant

So my boyfriend & I have talked about having kids & he’s been saying he wants one but i told him it’s not the right time bc I’m still in school & I work 2 part time jobs . He works in the oil refinery & . I feel like we struggle if we had a baby but there’s times were I think of having one . & we talked about it . But I drink a lot of coffee , usually one cup sometimes I won’t even finish the cup of coffee . But is it true that it can reduce your chances of getting pregnant every month?