The teenager, who this year celebrated her big day on the same day as Thanksgiving, posted a string of messages on her Instagram while spending the day with her family.
One picture showed her yesterday next to a picture of her on Alaskan Bush People when she was younger, with the caption: “Anybody else feeling old today?”
Another throwback photo showed her eating an ice cream with her “bestest friend” Tyler, with whom she shares the same birthday.
Meanwhile, in a third she smiled for the camera while wearing a party hat. Alongside that picture, Rain — whose mom Ami has recently been undergoing a second round of chemotherapy — thanked fans for sticking with her through “every tear, every giggle, every fear”.
She said: “You’ve all been here helping me and I can’t thank you enough, I love you all!”
Rain — who has more than 39,000 followers on the social networking site — has been subject to abuse online in recent months.
But in her message she also thanked those people who had “doubted” her, adding: “You made me stronger.”
Okay last birthday post I promise! I just wanted to thank everyone that has helped me through this wild place we call life, through every tear every giggle every fear, you’ve all been here helping me and I can’t thank you enough I love you all! It’s still amazing to me that I’ve lived to be 15 and it’s even more amazing that everyone I love has lived to see me turn 15 I’m so incredibly blessed! Just four years ago I was a shy little girl that was afraid to be herself. But now I’ve come so far I mean 39 thousand followers!!!! You guys this is amazing! Thank all of you who have supported me for you have shown me the power of helping others, thank you to the ones who have loved me you have shown me what real love truly is and even thank you to the ones who doubted me you made me stronger To my family my friends and my fans: I LOVE YOU❤️ #stayhappy #staystrong
Rain also took to Snapchat to give a message to fans, apologizing for not posting as much as she’d like lately, saying: “I’ve spending a lot of time with my sister, my family and my friends.”
But she added: “All of your messages are so adorable and so sweet, thank you so much for all the birthday wishes.”