Go back to the gp. There are several different triptans, sumatriptan is one of the first to be prescribed but there are lots of newer ones, sometimes one will work where others won't. It's trial and error with triptans. There's also injectable triptans which can work where the tablet forms don't. You do need to push for migraine treatment unfortunately, especially for the newer types of treatment.
Liquid or effervescent ibuprofen and paracetamol are the most effective for migraines because they're absorbed quicker.
When I feel a migraine starting, or get my aura symptoms, I take my triptans, antiemetic, co-codamol and effervescent ibuprofen in diet coke. The caffeine and fizz of the diet coke help the medication work slightly faster and drastically reduce how bad the migraine is.
You need to make sure you take the medication as soon as you feel the migraine starting or it won't work as well or at all. If you get aura symptoms before a migraine take the medication as soon as the aura symptoms start to minimise the attack or head it off all together.
Look at the migraine trust website. It has loads of information on all the different types of migraine treatment whether that's ones you take when you feel an attack coming on or daily medication to prevent attacks, again with preventative medication you may have to try a few for a couple of months at a time to find one that works. There are even treatments such as botox to help migraines if all else fails.