Metformin is not a magic pill. Most of us find that even at its maximum dose it will reduce your levels by 1 or 2 at the most. What works 10 times better than any diabetic medication is to change your diet and lifestyle. So ...
Get yourself a BG meter, if the doc wont give you one get an SD Codefree meter from eBay or Amazon as that is by far the cheapest way of self testing.
Do some exercise even if it just walking. Lose weight if you need to as excess weight stops what insulin you are producing working properly. As you reduce weight the insulin you are producing will begin to do what it is supposed to.
Cut out as much pure sugar as you can so not just soda's but sugar in tea, coffee, pure fruit juices, cakes, biscuits, sweets etc. Next halve your intake of rice, pasta, bread, cereals, potatoes and other things made from flour. Replace with extra meat, cheese, eggs and loads of green veg.
Test 2 hours after you eat and recognise that the safety limit is 8. The guidelines say you should be below 8 two hours after eating and between 4 and 7 at all other times. If you are regularly exceeding 8 then you are running risks of going blind or losing a limb, it really is that simple.
At the start you may find it difficult to get below 8 but look for a gradual improvement day by day. This can take many weeks and during this period you may find getting under 8 is difficult. Until things begin to settle down you can test before your meal as well and then judge if the meal was safe by trying to get your 2 hour after meal reading to be roughly the same as the before meal one.
If you still get a big rise in BG's two hours after a meal then cut down more on the rice, pasta, bread, cereals, potatoes and other things made from flour next time. You can try swapping the white varieties for brown so brown basmati rice, brown or tri-colour pasta and try Burgen soya bread that you can get from most supermarkets as that will help a bit.
All of this sounds difficult but it is achievable. Loads of members have followed the above advice or very similar and restored their BG levels to those of a non diabetic. It's not a cure but you can bring the disease under control.
If you feel you can't change your diet then you should go back to the docs and ask for stronger medication to keep your levels under 8. Recognise that stronger medication route tends to lead people onto insulin sooner or later which is why many of us do the "eat to your meter" way as many members who have followed the diet change route have seen no progression in the disease over a period of years.
Good luck and keep asking questions.