it may be the pictures but she seems small for 7 months :/ what are you feeding her?
just persist, be patient with her, she will understand the halter breaking eventually. I'm not a big fan of leaving the halter to drag due to the possibilities of it getting hung up on something, but if it works for you then all I'd say is be careful and keep an eye out. Tie her up every day for her feed, while she is tied, brush her or hose her down. If you cant get close enough to brush her, use a show stick and rub it along her topline, then you can gradually move closer. for walking, have her in a small yard where she cant get away from you. pull her in small circles using the pull and release method. you pull, and when she moves, release pressure on her head. this is her reward. release even if its only one step. if she plants her feet, pull her diagonally instead of straight forward. also, you want a rope halter with a ring in it. this ensures it releases the pressure, whereas the other one just keeps getting tighter. it may also help for you to walk her and have someone else moving behind her to get her going.
good luck and have fun, she is cute :)