If I could change one thing in the world, it would be the paranoia that our society has inflicted on all ttc or pregnant women.
As many posters have pointed out, eating raw fish is fine. There is a slightly higher chance of getting something that could make you/baby sick, but honestly, in this country where food hygeine rules are strict, it's frankly unlikely. And... as you have not got sick yet, I think you can rest assured there was nothing wrong with the sushi you were eating.
My doctors all told me that eating sushi while pregnant was just fine, but that I should be vigilant about where and when I bought it - ie not the last box from the chiller at the petrol station cafe on the M5!
Ahead of you being pregnant, let me also assure you that pasterized and non mouldy cheese is absolutely fine to eat. All cooked cheese is fine to eat. Foods high in vitamin A should be limited, but do not have to be avoided like the plague. Ditto foods with a high mercury content. Tinned tuna does not have a high mercury content so can be eaten as normal. [And I always ask myself, who eats fresh tuna and/or swordfish more than once or at most twice a week anyway? Similarly, who eats liver more than now and again!?]
On alcohol, excessive alcohol is known to be bad. Very limited alcohol (ie 1 - 2 units a week) is known to be fine. It's unclear where the line is between the two so, to be safe, stick to 1 - 2 units once a week or so.
Also, this is a great book that not only says what you can and can't do, but tells you why rather than giving you ridiculous rules with no guidance!
Hope you are pregnant soon! 