I'm so exhausted at 15 weeks it's starting to affect my mental health and it's so frustrating!!

I can't take lying in bed anymore. My doctor has checked everything and says I'm just experiencing normal fatigue but I'm so sick of being in bed napping and watching TV. When I'm working I fall asleep at my desk or can't focus because every part of my body feels tired. Then every time I get a small surge of energy and do something I want to do (cleaning, hobbies, light exercise) it feels like I'm paying for it for days afterward. I swam in a pool on Wednesday and I've been wiped out for THREE ENTIRE DAYS. I'm so frustrated and sick of this, it's making me depressed. I thought the second trimester would be easier but this past week has been brutal. I just needed to get this out without complaining to my husband, he's super supportive but I feel like I'd be ranting at him all day if I let myself. I can't wait to meet our daughter but most of all I want this to be OVER!