Combination feeding

If you need to stop then you do what's best for you.
Have you had him checked for a tongue tie? If it's painful it's down to the latch what did the lactation consultant say about latch? If he's not latching well he won't be transferring milk from the breast which won't establish your supply appropriately. Did she recommend power pumping to increase your pumping output? Remember what you pump isn't an accurate indication of your supply. What pump are you using? If your breast is hot or red you need to get it checked as you may need antibiotics.

I had him checked for tongue tie as his older brother had posterior tongue tie that we had released and it slightly improved the latch but not the supply.

My newborn’s is very mild that it shouldn’t affect the latch according to the doctor.

I’m using Medela free style (double). I’ll get checked tomorrow for mastitis.

Tbh I didn’t like the lactation consultant’s approach. She squeezed the “lazy” side and nothing came out then she said you need to supplement with formula to make sure baby’s weight doesn’t drop.

The main thing is he’s healthy and is gaining weight but will try a different consultant.

You're right if baby growing well is the most important! I think you are right about a different lactation consultant I've never heard of one doing that or encouraging formula except in exceptional circumstances. Was it an IBCLC?