Birth Control

I was taking a very low low dose of birth control recommended by my doctor to take for 3 months to help regulate my cycle. During those 3 months it was very consistent on time same length everything. I had 1 cycle after and now it's been about 3 months since I've had a period. All pregnancy tests are negative and I havent had any blood tests taken. Should I get a blood test to be sure or get back on the birth control maybe longer than 3 months to kick start my period?

**have no insurance atm***