Limited bc choices

Rachael
So I have a heart condition that means I can't have birth control with estrogen it. I've had the nexplanon (that I hated) and now I've tried depo shot but only got it once and I don't like how I've felt with it either. I've had one period with it and I'm at the point where I'm due for the next shot so does anyone know if you've only had the shot once if you can get pregnant right after that wears off? I've missed my period and I've taken a pt but it was negative. I have another test in case I took it too early though