Low ferittin (iron?)

Danielle

I just checked my blood results I am 7 weeks pregnant and it’s showing low ferittin everything else is normal hemoglobin etc but I have been extremely out of breathe so I’m assuming that’s why? How do I increase my ferittin or iron? And how long does it take to increase via food changes and or supplements. I’d prefer not to supplement if it’s going to cause constipatoon