When can I stop doing the c curl?

So my 5 month old and I have been bedsharing pretty much since the start and I love it. I follow the safe sleep 7 and have always slept in the c curl. However, I’ve suffered with really bad SI joint pain for the past couple of years, which is really aggravated by the c curl. I wake up every night in agony and have to take painkillers (hate this as I’m breastfeeding - they are safe but would like to avoid them still!).

From reading online, sleeping on my back would be much much better for my SIJ pain, so I’m wondering, is it safe to sleep on my back with baby at breast level, my arm curled around her still? Are there any risks to this sleeping position? Thanks!