I unnerstand the inital worries in your first pregnancy,it would worry me too! Perhap the reason you worry so much when pregnant is because of how your first pregnancy started,there is always a trigger for people who suffer anxiety and I think this is yours! Yes,you didn't know you were pregnant but you can/could of avoided drinking and drugs,so now you want to control as much as you can during pregnancy by avoiding anything that can be avoided and potentially cause birth defects. In becoming so worried you become obsessed and really beat yourself up about things and become irrational without looking at the bigger picture.
We all know heavy drinking,drugs and smoking can potentially cause harm to an unborn baby and that is why pregnant women (for the most part anyway) avoid those things. But when it comes to food and toxo and other things,the real odds of anything like that actually doing any harm are slim to none,especially if its just a one off or not done often or on a regular basis (like eating pate and having the odd drink). I fully get that the lamb thing has freaked you out,but even then,the odds of it having caused any problems with the baby are very slim,as like mentioned before,you are probably immune anyway,but because it could of been avoided you're really beating your self up about it and worrying far too much. Remember that you did not know you were pregnant at the time,ttc yes but that doesn't mean you have to be anymore careful about what you eat anyway,I think the problem lies with the fact you didn't avoid it,just like you didn't avoid drink and drugs first time around and its triggered this anxiety in you again.
I think if you become so focused on controlling/avoiding certain things you will stay in a state of anxiety for the rest of the pregnancy,and that will ruin it for you. Seeking therapy for the issue will help you to overcome this and you must also remember that there is no need to change your diet in pregnancy,you should carry on as you normally would,eating foods you normally would,the only changes that really need to be made are perhaps eating a bit more fruit and veg and cutting down on liver and pate consumpsion and of course,avoiding cat poop,drugs and alcohol,although the odd drink here and there is fine,and quit smoking,but I doubt you're a smoker anyway!
I know I sound like I'm lecturing you,I'm not,I'm just saying what I see and what I've learnt in my own therapy sessions :) My anxiety isn't completely cured,but its far better than it was and I'm much more in control of it now as I know what my triggers are and have had,for the most part,my rational train of thought put back on the rails lol.
I really do hope you can get sorted asap,pregnancy really should be a joyus time,not one of fret and stress but with any luck some form of therapy will help make this happen for you :) Good Luck xx