TTC - feeling hopeless

Hi guys i have 2 kids already my youngest being 3. I got on the depo in 2019 the last shot I received was on October 2019 . I’ve ben trying to conceive since and i can’t! I feel useless and hopeless. I’ve tried tracking my periods my ovulation days everything and nothing. This month for some reason hit me the hardest when i got my period and wasn’t pregnant again 😕 I feel like an emotional wreck ! I just don’t understand why 😭 sorry if this is selfish of me(having 2 kids and all) but i just need to vent cause no one understands this feeling its hurting me inside so bad.. anyone else have issues getting pregnant after birth control ?