Should my thyroid (tsh) levels be under "3" before trying pregnancy (ie to insure a healthier pregnancy)? I have hashimoto hypothyroidism.

Depends. A TSH level of 3 determined 24 hours after the last and immediately before taking the next pill indicates that the thyroid hormone administered is sufficient - if if was taken within hours of taking a dose of thyroid hormone, the amount of thyroid hormone administered may be too low by the time you will be taking your next dose.
ok to get pregnant. Although a TSH level between 1 and 2 would be ideal, there is no reason why you can't try to become pregnant with the present level. Once you are pregnant you will likely need a higher dose of thyroid hormone to keep the TSH in the ideal range, so you should be tested as soon as you know you are pregnant.