Should I start learning to play the cello?

I've played the flute for three years in my school band and got a good general understanding of music and the instrument (I was pretty good at it and loved it). For the past year I've been self-teaching myself the trumpet and actually like it. I now play the trumpet in my school band and that is my 'primary' (though not my best) instrument, and I no longer put much focus on the flute... Knowing this, would it be unwise to pick up the cello, too? I'm planning on renting, not buying; I also have ample time to practice both trumpet and cello but I won't have a teacher.