I've developed health anxiety postpartum & am worried about a mole which my derm says is fine after dermatoscopic exam. Should I be reassured by this?

Reassured, derm. Yes you can definitely be reassured if your dermatologist looked at it. Of course you may always seek a second opinion, or even request to have it removed, which your family physician or dermatologist can do. More importantly, you mentioned developing some anxiety post-partum. I strongly encourage you to bring this up to your family doc. Post-partum depression or anxiety is a real diagnosis.
Yes. We all have moles. You can keep an eye on the mole and consult your doctor if it grows, changes color, starts bleeding, or develops a nodule.
There are moles and. then there are moles. I would trust your dermatologist. They are real expert when it comes to skin lesions like moles. However, what are you doing for help with the anxiety you have developed postpartum? Please get help for that - life will be more pleasant. Take care.