Working while pregnant good or bad?

Victoria
I work retail and it's a lot of walking around, multitasking and sometimes very overwhelming. I'm about 10 weeks and just got promoted to assistant manager training. I haven't mentioned to my store manager that I'm pregnant because of the new promotion. I don't want her to feel like I'm going to let pregnancy affect my work ethic since another co worker is also pregnant and has been calling out a lot due to morning sickness. I've been having a lot of nausea every morning and throughout the day but I just deal with it. I'm thinking it's all bad timing. I'm afraid all the pressure is going to end up to be too much for me while pregnant, but this is a great opportunity for mine and my family's future. Am I over thinking?