15 weeks feeling so exhausted

I've been feeling exhausted for the past two weeks. I work out 20 min a day per my ob. I may not eat as often as I should and my iron is good. I'm a ftm and i feel so exhausted. When I work out and shower I'll feel less tired but then an hour later it's back. Has anyone else delt with this. I even feel tired from the time I get up. Never had any pregnancy symptoms like morning sickness, just hunger, frequent urination and acne which finally is getting better.