What is stopping you from pulling it back? Is the tip too small? When it's not erect can you put your finger inside it and slide your finger around your glans? If it's just too tight, all you need to do is stretch the opening a little every day until it will roll back.
It is really much nicer to have a foreskin that rolls back easily when having sex. Your pleasure is immensely better and hers too!
A few men live their entire lives with a non-retractable foreskin. They can masturbate, have penetrative sex, get married, and father children with a foreskin that does not retract. Some believe that a penis with a tight foreskin is more sensitive and that sex is better. However, most men prefer to make their foreskin retractable.
Almost all boys are born with a foreskin that does not retract. This is normal. It takes years for the ability to retract to develop. About ½ of boys have a retractable foreskin by 10.4 years of age. Many adolescents still have foreskins that have tips that are too narrow to pass back over the penis head. These foreskins may be gently stretched over a period of time to cause them to widen.
You are normal for your age. Your foreskin is still developing. You can help it develop by stretching it.
When your penis is erect, gently pull your foreskin back against the head of the penis. As the head attempts to pass through the foreskin it will stretch the skin a little. Do this every day and in a few weeks or months your foreskin will widen and you will be able to retract your foreskin. Do NOT force retraction.
It works by tissue expansion. Stretching skin induces “mitosis” which is a word that means “division of cells”. New skin cells are formed and the skin expands but it takes some time. The increase in size is permanent. Be patient and let mitosis do its work.
The important thing is to put the skin under tension every day so that it will grow wider.