I didn't read through all the replies here, so if I repeat something someone else said I apologize. My main thing I tell beginner riders, or riders building back confidence, is the wonder of groundwork. Lots and lots and lots of groundwork. If your horse doesn’t respect you 100% of the time on the ground, and trust in you as a leader, you will have a horrible trail horse.
I like to use more of a natural horsemanship style when I start building a good trail relationship. I’m 5’4” and 115 pounds, so I don’t have much strength. I like to just a training stick/whip and a simple rope halter.
I start by doing lots of hand walking. The horse has to keep in perfect step with me, and stop the second I do. It seems to become a sort of game to them after a while. If the horse crowds my space or starts the walk ahead, I give them a gentle tap with the stick, stop, and make them back up and do it again.
I like to go jogging with my horse. I put on my running shoes and go for a jog with them just like a would a dog. I like to stop suddenly and give the horse a smart tap on the chest if them don’t stop the second I do. It makes them pay 100% attention to you and ignore everything else. If they’re watching the scary dog across the street, they might not notice me stop! I also will do what I call the old lady walk, where I take tiny slow steps and the horse has to barely move to stay in step with me.
I also work on flexing, giving to pressure, and simple things like picking up their hooves. I’ll stop randomly on the side of the road, or along the trails, and make them pick up their feet, flex at the pole, or just a couple leg stretches. It helps relax them and show them who’s in charge. Horses LIKE for someone to be the boss, it takes that worry away from them.
Keep walking her for a week or two until she’s 100% relaxed and comfortable wherever you lead her. You’ll also notice that YOU will become more comfortable and will have more confidence in your horse. Challenge her as well while leading, make her slop through puddles and go through brush and trees. Walk her calmly past barking dogs or loud vehicles. She’ll start learning that there’s nothing to fear and spook at when you’re with her. The transition from you being on the ground, to you on them bareback or in the saddle barely even registers to them.
I hope this helps, and good luck! I’ve been where you are and I once again LOVE anything that challenges me and my horse.