External flash should have been used no doubt for these particular shots. I think that could have been avoided if you just planned and positioned them a bit better. Your compositions arent good. The first one, aside from being too dark, the bottom of her dress is cut off. Also, that tree trunk in the back is fighting her for the attention. Also, looking at her forearm...she appears VERY tense. The second one, should have been centered and brought up more so none of their feet were cut off as well as the additional lighting. Most important advice, never cut off the feet, toes hands or fingers when doing full portraits. Its ok when getting in tight and for certain "creative" type shots.