Congratulations, how exciting!
The official guidance would be no contact with pregnant sheep. When I was pregnant, my midwife said that is what she would always recommend for someone who had little regular contact with sheep, but for someone who was handling sheep on a daily basis, the risk would be less. I was in this situation, so the advice I was given was absolutely no actual lambing sheep, no touching amniotic fluid, afterbirth or wet lambs. So I was still doing checking the sheds, feeding, and I did deal with any pet lambs or lambs that needed topping up and so on, but only once their coats and navels were dry.
I THINK I was told that the earlier in pregnancy you are, the less likely you are to catch anything and it then transferring across the placenta, but if you do, the consequences are likely to be devastating for the baby. The further through your pregnancy you get, it is much more likely the baby might be affected, but as he/she had done his/her main developing and is just growing, it would not be such a big effect. I think it is something you need to decide together.