do not write first, then talk to your boss honestly and frankly
tell him 由於 lp工作變動,我必須按時走去接孩子,其實我晚上還會幹, you always make the time up. You always work more than 9 hours every day. You will work more, you want this company to succeed, if the company is good, you are good, blabla
You are on the same boat with your boss.