Everybody has regular rhythm, but they use it to walk on two legs without falling down. I knew of many fellow students of my teacher who sped up and slowed down randomly, or depending on how hard the piece was (slower for harder). Both practices were not pleasing to listeners.
The trick is to move the skill of rhythm from walking, to playing piano.
I suggest counting one two three four, as you walk. You obviously walk in rhythm, you haven't broken any bones lately from falling. People with some nerve disease like MS are excused from this exercise. Count continually aloud or in your head, every time you walk, until counting is as natural as walking is. Walk fast on the way to the next class, walk slowly looking at a sunset, but walk and count.
Then after some weeks of this, count in the same way you have trained yourself, while playing the piano. If you can't read the music and count at the same time, slow down and play one hand at a time. The accuracy of the rhythm is what matters while you are learning this skill. You are your own metronome, but you have to connect the skill of your feet, to your hands .
Don't change rhythm speed for emotional reasons until you have played in strict rhythm for a couple of years. Chopin is no composer to use as a teaching source for young students with rhythm problems.
Piano teachers can criticize bad rnythm, but I don't know of any who has used or endorsed this method. But man has been walking in rhythm since he stopped swinging from trees as an ape. Use your reflexes, don't ignore them.
good luck.