Semen is not so thick

I am 30 years old unmarried guy. Actually since 2005 I was noticing some semi solid small pieces in my semen so I consulted to an Urologist and He had my semen analysis done which came out as very low sperm count 16 millions/ml so he asked me for Scrotal Doppler test which said that "I have some dilated veins which shows reflux during valsalva's manoeuvre." So he operated 'Bilateral Varicoelectomy' in 2006 to remove those dilated veins. After surgery I had sperm analysis done at regular interval through out the year 2007 and sperm count was not so high but somehow was satisfactory i.e 20-40 milions/ml on an avg.
But what I observed in these 2.5 years of surgery is my Semen is not so thick as it was before surgery like jelly and semen quantity or volume is also not as much as it was used to be. Now a days it is 2-3ml only while normal volume what I read over Internet is 5-6 ml so pls let me know what can I do to increase my semen volume and thickness without taking any medicins only natural diet.
Also for last couple of months I am noticing that at the time of ejaculation my last 2-3 shots of semen comes out just like water while initial shots are not that much thick as it used to be. Anyway this happen when I am ejaculating once or twice in a day but if I abstain from sex for 2-3 days then still atleast last 1 shot comes out like water. So pls advise me some solution and answer all my queries asked above.