it's been 2 months since my last period could i be pregnant?

Hey ladies! my fiancé and i have been trying to get pregnant for about 5 months now. Today would mark 2 months and 5 days since my last period. i've taken 3 pregnancy tests and they are all negative. My dalima is that i've gained a few pounds (which is noticable on me since im a stick), my breast especially my nipples have been sore, and i've had nausea here and there. Could the at home tests be wrong? should i try again and buy the most expensive test? any thoughts?😌