have anyone that's TTC bounced back and forth between really wanting other try and wondering if you…

have anyone that's TTC bounced back and forth between really wanting other try and wondering if you should be?. I know I'm mentally ready for one child but my fiancé has 2 possibly 3. I love these kids to death and put them before myself and treat them as much as I know I'd treat my own, but I'm not sometimes not sure if I'm ready to handle 4 at a time. their mom has a possibly of losing them if she keeps messing up and sometimes I think I'm ready to take it all on and other days I think that I'm not... I'm so conflicted.. and sometimes I just think that it's because we have been trying for 7-8 months...