This is a useful link that might help. It is a paper by a doctor on dosages.
Fish oil: what the prescriber needs to know
Leslie G Cleland email, Michael J James email and Susanna M Proudman email
Rheumatology Unit, Royal Adelaide Hospital, North Terrace, Adelaide, Australia
"Investigations across a variety of inflammatory diseases have used doses of fish oil that provide daily intakes of LC n3 PUFAs that range from less than 1 g to more than 6 g [8].
Collectively, these studies indicate that the anti-inflammatory dose of fish oil requires delivery of 2.7 g or more of LC n3 PUFAs daily, and that higher doses are also safe and effective. A daily intake of 2.7 g EPA plus docosahexaenoic acid (DHA) is provided by a daily dose of nine or more standard fish oil capsules, which typically contain 30% LC n3 PUFAs w/w. People who self medicate with fish oil generally take one or two capsules daily. This is insufficient for an anti-inflammatory effect but it may provide cardiovascular benefit."
http://arthritis-research.com/content/8/1/202
There are no definitive answers, and I am not an expert and cannot give specific advice. I can only point you to research.
Intake recommendations range from 300mg to about 2.7 grams of EPA and DHA Eg 1.4 each.
A trial suggested uptake drops of in women at about 2grams of DHA a day.
For me quality bottled is cheaper and a better option for higher dosages. Check the label for amounts of DHA and EPA. A mix of Cod liver and fish is prudent due to the A and D levels in cod liver.
The body stores the mother Omega 6 but not 3 so historic stores have to be factored in.
As illustrated by the above it is as much about too much Omega 6 as too little 3.
Long chain omega threes in fish oil can thin blood and cause problems for small number of people so please talk to your doctor about dietary change.
RB