Using the formula of 3 times gross annual income, use an online mortgage calculator to get an idea of what the payment would be.
Many of these calculators will let you plug in the anticipated rate of interest, expected insurance and taxes.
Use just the information that you have, leave off the insurance and taxes, and estimate the interest.
This will give you a base rate for the monthly payment of just the house.
Use this based monthly payment, tack on about 25%, and you’ll have a safe estimated idea of the full monthly mortgage payment.