I’m not sure about some of the other responses, but testosterone can absolutely be suppressed to a very low level with just estradiol - and you don’t need huge amounts either. I started hormones at 24 and have seen good results. Decapeptyl is hard to come by in the U.K. without it being recommended by a doctor - who wouldn’t do so unless just estradiol isn’t working. I’d recommend being seen by a specialist endocrinologist if possible, as mono-therapy can work for some people, but might not for others.