New job and potential pregnancy

[FrostyPopThePenguinLord]

I'm starting a new job next week and there is a very real chance I could be pregnant. We are actively trying to have a baby so this is by no means a shock but I'm just a little unsure of how to proceed as I feel a bit stuck.

I previously suffered an ectopic pregnancy in January and therefore I'm massively paranoid about every little twinge and pain (is it pain from another ectopic or just my period starting etc), and if one more person tells me to just relax, what will be will be, I'm going to gut them with a dull plastic spoon....

It's quite a physical job with animals, not hugely heavy and dangerous but it's still a feature of the work and I'll be on my feet all day.
I've had advice before saying don't tell anyone until 12 weeks+ just in case they are not happy and in an ideal world I would do that, it's just I'm so nervy about it and I think the worst about every little symptom so I kind of want to tell them as soon as I know so they can be understanding if I need additional medical appointments or if the work needs to be modified slightly.

In reality I'm going to wait as long as I can (hopefully out of my 3 month probation period) before I have to say anything as my body won't have changed much physically to look at so I should be able to do my job without any issues in that regard.

Symptoms are going to be an issue, there is a fair amount of blood and guts to deal with and I have a stomach of absolute steel in normal circumstances or I would never have agreed to this job, but in my previous pregnancy I was sick very very early on, I don't want that to become an problem with regards to doing my job.
It's very much a mans world in this industry as well and I don't want to be the 'problem' woman who can't just get on with her job without 'wimmins thangs' messing it up for them.

I feel bad for the employer because I might only be able to do my job for a few months before being unable to and there is training involved to even be allowed to do the role, so I could have to go on maternity leave and they have to train a whole new person to cover for me, I could understand if they were annoyed.
I know I won't get maternity pay, I accepted that when I knew I wanted to change jobs.
Although I'm planning to have a Csection I would still want to get back to work as it's a job i enjoy and can progress in so I'm quite anxious not to fall too far behind in whilst it's still developing.

I guess I'm worried that it might affect how the company treat me, I don't want to be descriminated against but at the same time I can see from an employers point of view it's a bit shit to train someone new just for them to announce they are pregnant and can they please bugger off and grow a human for 6 months to a year.....
Sadly it's not an option to remain jobless....I wish I was a kept woman had that luxury.