Im starting to lose hope :(?

my last withdrawal bleed from the last month of birth control started on September 1st. Since then i stopped taking birth control with hopes to conceive our first baby. We did the BD on the 17th and 18th, i felt what i thought was ovulation pain on my left side on the 19th. Since then,however, i feel constant cramping in my stomach almost like period cramps. Im not due for my period for another week and a half. does this mean that my egg didn't get fertilized? i was really hoping this would be our month and now i'm starting to lose hope. did anyone else experience this and still end up being pregnant that month? baby dust to all TTC's :)