Over the holidays I've been allowed to have both my ears stretched to 3mm but now there really loose and keep on moving about. I've had them about 3/4 weeks but I don't know if I should get the 5mm size or leave them..

Do it gradually otherwise you'll mess your lobes up. Minimum wait should be around 2 weeks before you can up the size just keep them clean and don't knock them and they'll be fine.