She is 4 years old and I have been having lessons for 6 months. Sometimes, she is absolutely fine but others, she does really pull on the bit. I worry in case my hands are holding her too tight, so I try to be cautious of this. My instructor is very good but whenever I have lesson, she does not do this.
she's only 4 give her some more time, she will get the hang of it.
ask your instructor about how you can improve this, but i dont think you are going anything wrong, i think sometimes people tend to pull back on a horse when they start leaning, so maybe try and give her slighty more rein but then take up the same contact again so she learns that the contact will be there and she will learn to accept it.
she will have good and bad days, i find my horses are better in lessons i think its because they get you to think of other things so you dont conerntrate on a bad habit too much