You are meant to go to A&E if you have sunburn larger than a hand size / white areas which indicate deep burns - you could go into shock - Please ignore your mother she clearly does not understand and get yourself to the hospital.
When to go to A&E:
Severe sunburn: If you have blisters, significant swelling, or a high fever (38°C or above, or 37.5°C or above in children under five).
Symptoms of heat exhaustion or heatstroke: These include feeling very tired, dizzy, sick, or having a headache and muscle cramps.
Suspected dehydration, shock, or sepsis:These are serious conditions that require immediate medical attention.
Any burn to the eyes, mouth, hands, or genitals, even if mild: These areas are more sensitive and prone to complications.
Large burns (larger than the size of the palm of the hand): These burns require specialized care.
Deep burns that cause white or charred skin: These indicate a deeper burn and may need specialized burns unit care.
When to see a GP or call NHS 111:
If you have blisters or swelling.
If you feel unwell or have any concerns about your sunburn, especially if it's over a large area.
If you have a high temperature (fever).