i'm worried about my girlfriend she is cutting herself :(?!

i'm worried about my girlfriend she has depression, she is a 14 years old mother (by mistake), and we are being kicked out tomorrow and she has already been kicked out of her parents house. i'm scared because she has been dressed in dark clothes the past two days and since yesterday night she has been keeping her arms covered. well today when i went to the bathroom she was putting her shirt on (she was done taking a shower) i know i shouldn't have just walked in but we do that all the time now because we are getting married in a few weeks hopefully but i seen her arm and she has been cutting herself. she has very bad marks like really really bad and they look like she got very deep in her arm with whatever she used. should i talk to her because when i asked her to let me see her arm she said no and walked away from me. could she be doing this because of everything going on right now? i'm very worried she is very depressed and she won't tell me what is wrong i ask her over and over again and i have bagged her to tell me and she said it's nothing. those marks do not look like nothing can someone help me please.