TTC and job insecurity

I'm 37 and TTC since January of this year. I was made redundant from my job last year so me & husband decided to put off ttc until I found a new job. I now have a job but wont have job security until after I've worked for 18 months. Logistically, to make sure my job is secure before taking maternity leave, we would have to put off ttc until 2020. Bad idea considering my age. We also both need to have secure employment to buy a house eventually. I want to be sensible but also realistic. What are your thoughts?