working

I'm almost 18 weeks and I'm totally embarrassed to say but I'm struggling with work. This is my first pregnancy and the sickness was very rough on me thankfully it's passed but the headaches and backache has replaced it. I've worked for 9 years in jobs where I have to stand all day and it's never bothered me as much as it does now. I feel like a failure and I just want to cry I wish I could go on maternity now! I can't tell anyone how I feel as they just laugh and tell me to wait until I'm 30+ weeks and I won't cope etc. I do have quite a big bump everyone is always shocked I'm due in March! Just wanted to see how everyone else is doing standing all day and stresses of work!