Last period 7 wks ago, darker larger areolas, 3 faint positive preg tests at home--but several neg's, & neg blood test at dr. could i still be preg?

Pregnant ?: The statistical odds of pregnancy at age 45 are extremely low, so if the serum pregnancy test was negative, you are probably starting the menstrual irregularities associated with "pre-menopausal" changes, and not from pregnancy. This may revert to a regular cycle with somewhat heavier periods, but ask your gyn provider about low dose oral contraceptives, if not contraindicated.