Oil baseboard heating not heating up the house

As title stated. We live in a 5 zone house with oil baseboard heating whenever the outside temp is under 40. It struggles to heat up to desired temp. E.g. I would set the temp in a zone to 68 and the temp would get up to about 66 (very slowly) and then stays there and never gets to 68. We bled the system at the beginning of the winter and all the pipes out of the boiler (Biasi) are hot.

We recently moved into this house and it’s our first winter here so we don’t know if this is always the issue.

I’m assuming the existing BTU is sufficient for the size of the house. What else could be wrong here? Thank you guys in advance.

Edit: as one of the commenters suggested the thermostat was not calibrated right so I turned the heat higher and the temp came up in the house. Thank you guys! I’m gonna look into heat pump this year, oil heating is expensive