preggy ba or not?

Hi! Im new here. Im trying to seek opinions and advices kung buntis ba ako or hindi. Regular menstruation ko since then, I had sex ng November multiple times sa partner ko. Nung November hindi na ako nagkaroon and December, until now. I took a pregnancy test twice, and it was negative. What should I do? Kasi mag 3 months na ako di nagkakaroon. Ano din yung ways para malaman kang buntis ka ng di lang pregnancy test ang ginagamit? ano pa pwede gawing test?