Please Any help is appreciated :)

I have a few questions that i probably should know but i dont , Im sure some women can help me out hahaha! Okay I am a mother of 1 , last night he asked me if I am pregnant, which wasnt on my mind until now because im wondering why is he asking me this? He didnt ask me that during my first pregnancy so im finding it kind of different ... Anyway since he has asked me that question i have noticed a change in my sons behavior , not sure if it is part of a 3 year old toddlers growth or what because again i am a first time mom , When pregnant with a second child does the first child behavior change? Also, would he know im pregnant before me? Andd last question what are the chances of me being pregnant with us having sex the day before my ovulation day? I appreciate all comments, Advice and/guidance -- Thank you in advance :) SN : I attached my ovulation calendar as well for a visual.