We are playing Tomb of Annihilation, which is 5th Addition. I am a young, 1/2 elf female and my name is Shakida. So far I was recruited by a prominent citizen to participate in the adventure to find the source of a curse. Then transported to Chult with an Orc and became part of the group traveling through the jungle to discover the source of the curse.
I need to figure out where I am from (?), why I left home.
I am thinking something like: I am from a small village not far from a big City, I traveled to the city with my horse race, and when I won all the races, I was accused of cheating and got beat pretty bad, dumped on a boat while unconscious and transported downstream to a strange port.
Nice. I played part of TOA, but my group stopped due to some scheduling issues. Chult is a fun setting. You sound like you're already doing a decent job coming up with a working backstory though. Here are a few little thinking prompts I like to use when I make new characters:
-Create three rumors about your character. One false, one true, and one partially true. Coming up with an explanation for the false rumor is a fun way to add flavor to your character.
-Come up with two or three people your character may have known in their past/current life. Could be a friend, mentor, family member, enemy, etc. It helps make your character's past life or hometown more colorful and your DM might work these NPCs into the story.
-What are three things your character likes and dislikes (could be literally anything: food, music, habits, etc.)
-Does your character have any quirks/habits?
-What is your character's background? I don't know if you've read the ones in the player's handbook but they are examples of backgrounds. In my games however we don't typically use these exact backgrounds and instead create our own because they're a bit cookie-cutter and bland sometimes (you'd have to ask your DM about this though). Backgrounds are a great way to narrow down your character's motives and how their former life would bring them to become an adventurer. Your background is even more important than your class because it describes how your character fits in with the world (which is why I dont like using the exact ones from the PHB because they can be too limiting for such a creative game).
Once I think about these prompts a bit, I find creating a backstory becomes easier because I have a better idea of who my character is and how they respond to situations. You've already got some interesting little details about your character, and I hope these prompts will help you further define them. Figuring out why you would join an adventuring group is often the hardest part for me, and sometimes it helps to talk to your DM so they can help pull your group together. Again, sorry for the text wall, but I hope this helps!