Your real estate agent or builder may recommend a home mortgage service but be aware this may not be the best match for you. Many real estate companies and builders work with mortgage companies to help qualify home owners, but this may not be in the potential buyers best interest.
If you feel that you are being pressured into a mortgage that is more than you want or that will be cost prohibitive for you to make the monthly payments it is important to simply let the mortgage company know your limits and stick with them. If you are pressured after this it is best to find another company that will work with your comfort level rather than trying to push you into something you don't want or can't afford.