What bothers me is that in those three months I 've had injures I never had when I was in powerlifting and certainly not in three months only
Of course it ain't enough and I can not really think of anything to fill in this gab (being powerful enough to sustain the mistakes of my colleagues) without burning out.
power lifting give strength in a somewhat linear fashion. your muscle might be strong, but your joints might not. aikido tends to put rotational stress to your joints which i believed you are not used too or trained to deal with through power lifting. muscle strength in this case might be detrimental to your practice, because it can be used to further increase the stress on your joints when techniques apply to your body, i.e. if nage applies rotational component to your joints, and if your put up some resistance, your muscles will increase the stress on your own joints many folds.
so try the opposite approach, being weak enough to protect yourself. strange and confusing, yes?