Thank you for your question.
From what you describe your ejaculation time is normal. The duration varies from 5-15 minutes and anything within is normal. You can learn to extend the time by practising focussing on sensations when masturbating and using your pelvic floor muscle contractions to prolong the time gradually. It comes with practice. You may wish to read 'New male sexuality' by Bernie Zilbergeld. Please notice that when you feel anxious or stressed or upset the ejaculation comes sooner. When you are relaxed youb can make it last longer.
hope this helps