I would like to increase one cup size (B to C). What to try first - fat transfer or implants?

I am a 36 year old woman. I I have breastfeed two children for a combination of four years. I loved how my breasts looked while I was pregnant. I would like to increase one cup size (B to C) I weigh 140lbs at 5'4. I tend to be a bit more conservative with my body and I'm not looking for a dramatic look - I prefer natural and if family/friends can't easily tell a difference. I am considering fat transfer to my breasts. I like implants but I have sensitivies to metals and food allergies so am wary of BII. Should I do fat transfer snd go to implants later if I am not satisfied with volume increase, or go straight to implants? Are implants more complicated after a fat transfer?