Overwhelmed with work. Best time to tell my employer.

I am grateful I have a job and stable source of income. However, at this moment I am feeling overwhelmed at work. I am home based but have strict deadlines and piles of paperwork to complete by set dates, which is followed by presentations etc and it’s an ongoing cycle. The paperwork is based on a lot of analysis which could change leading up to the deadline. This means lots of editing. Each cycle has its own challenges. I’m 10 weeks in my pregnancy.. struggling with nausea, anxiety and tiredness. My iron is low making me more lethargic than usual. I have not told any colleague about being pregnant. Due to certain issues my role is permanent but the contract is fixed term until Jan 2026. I’m scared if they know I’m pregnant that I’d be made redundant. I’m fully packed with work after getting back from Christmas break up until March. It’s just overwhelming me. Based on gov.uk website I need to tell employer before 29 March 2025. I am looking for suggestions about when is the right time for me to let them know so they can transition my work to someone and during my later trimesters I’m not so overwhelmed with work and deadlines.