"My hearts won't go up when I'm on my survival world."

"When I get on my survival world there is nothing wrong in it but my hearts. When I lose one heart it won't come but, even when I eat food. This keeps happening even though I reload Minecraft. I have to kill myself to gain my hearts again. I don't know why it is doing this because I am wearing armor. I keep checking my settings to see if anything is wrong but nothing works! It is kind of irritating and I was sure this is some sort of bug. My sister also has this trouble. I have updated Minecraft so a lot of the glitches should be gone. I hope you are able to fix this, so I can play Minecraft normally. Thank you!" 🙂