FTM and first year teacher

Baby is due middle of March, right before spring break. I didn’t find out I was pregnant until I had already applied and been offered various teaching positions. This is my first year teaching, which is already a challenge! During my first trimester, I was constantly sick to my stomach and barely held it together. In the second trimester I finally started to get my shit together at school and at home. But now (32 weeks) I am getting tired so easily. On the weekends I sleep all day! Coming back from winter break at the beginning of this month, I noticed my patience has been wearing thin. My heart burn has been getting worse, headaches are worse, dizzy, sweaty even when it’s in the 30s outside! My OB says I look fine, so it seems to all be typical symptoms. But I feel so terrible because I snapped on my last class today. They are notoriously my most misbehaved, and the ones that did try to pay attention and encourage their peers to, were met with a “shut up” from half the class. That made me lose it! Already disrespecting me, then deciding to disrespect the peers who were just trying to help… I ended up raising my voice, which because I usually speak softly, just sounds like a yell. Rambled about being disappointed and how they can never come in and get started on their work. They were still snickering and talking, they do genuinely know better. But out of my 20 kids, 10 of them all seem to be BEST friends. So no matter where I move them, it’s always a challenge. I hate being yelled at, or having anyone raise their voice at me. And I told the kids that I did not want to raise my voice, did not want to scold them etc…they continued to laugh. I ended up getting them to quiet down enough to move on with the lesson. But it sparked horrendous heartburn and a headache. Genuinely felt like I was going to either puke or faint. But I pushed through. My anxiety has been getting worse and worse. Overthinking every little thing. I am trying to figure out how to manage these emotions? Especially because a lot of it is the hormones. I know as I get closer to the due date, my emotions are only going to get stronger, so any advice on how to wrangle them in so I don’t explode on a student?