hi, i sympathise with you so much, i am preg with baby no 4 and have had horrible eczma with the first three pregnancies, my skin was basically allergic to pregnancy with ds1 an ds2, i had it all over including my face
it wasnt so bad with ds3 and this time (i am almost 39wks) its not been too bad tho i have just had to take steroid medication to get rid of some really sore eczma on my hands and feet.
basically when pregnant i just moisturise, moisturise moisturise and on the really sore bits i use eumovate cream which my dermatologist has said is ok during pregnancy.
i also take piriton tablets as these help the itching a bit and they are deemed 'safe' in pregnancy ( i have taken them with each pregnancy)
i always try really hard not to take anything but sometimes that just isnt possible.
i would ask for an urgent referral to a dermatologist, they will be better placed to treat you and know which treatments are ok in pregnancy (it varies depending on the stage of pregnancy) most gps will just err on the side of caution, but a dermatologist should have or be able to find out which treatments are suitable for you during pregnancy.
good luck and i hope you get better soon, you may find as the weather gets warmer that your skin improves, cold weather and having the heating on etc tend to make eczma worse.
oh in response to the last question i have used steroids around the time of comception and all my boys are fine not recomended but the theory is that you could possibly absorb the steroid cream in through your skin to your blood stream and then through the placenta to the baby, the likelyhood of you absorbing enough to damage a baby is VERY VERY slim, but as always we err on the side of caution.