Please help! At my witz end

So my 3 yr old son has been getting really mean and aggressive lately. Since about mid august hes been attacking me mostly but now hes hitting my husband and mother. We even had to temporarily place our dog with a family member so he stops hitting the dog.

It started with simple smacks when he didn’t get his way. Then punching and kicking. Now we have escalated to screaming and punching kicking biting yelling i hate you. Im 8.5 months pregnant and have run out of ideas to discipline him. My husband only wants to spank and do time outs. Hes not helping in anyway.

Ive tried time outs, spanking, taking toys away, charts. talking with him about his anger only makes it worse. He just gets right in your face and spits or punches u harder. Drs say its just a phase and offer only time outs and stickers. My oldest never did any of this so this is all new to me. All i had to do with my oldest was speak loud and stern and she corrected herself. The mom voice is not a thing with this one.

What else can i try? Im open to all suggestions. He has zero care that he’s hurting anyone and im afraid he may hurt the new baby when she gets here.