Hi Martin, I too have recently made it to 5k and been running the distance for a week now, feels great when you can actually tell someone a recognisable distance that you run, instead of "around the block a couple times" 
To answer your question, I am a 19 yr old male who started running 2 months ago and my first timed 5k I completed in 31:04 which means for you a 28 yr old who is admittedly overweight, 33:04 is brilliant and to have made such progress in a short time to be at 29~ mins is fab! you should be really proud of yourself!
As far as what you are doing, if you are making progress it might seem straightforward to continue what you are doing. However myself I like to have a slow run on the weekend (Or whatever day suits you) where I try to increase my distance each week. this could be another 3-400 metres a week, and it adds up rather quickly. I do this so I don't risk a massive injury, which to be frank you are likely to recieve if you are going all out 4-5 times a week running fast 5k's.
Take a look at the training section on the site and decide what your goals are.
There are plenty of 5k to 10k programs out there which is what I'll be moving on to, and they give you a nicely structured plan that will minimize the risk of injury. On the flip side if it is just speed at 5k runs you want then increasing your slow run distance has been proven to improve with shorter distance running too.
I am sure others will chip in but that is my 2 cents.
As I have said before well done with your progress so far! Regarding your legs Martyn you could give weight training like squats and lunges a go instead of one of your daily runs, this would help strengthen them up a bit.
Hope I have got some sort of decent advice somewhere in that wall of text
Good Luck!