What size horse in hands would be the right size for me and I'm 162cm and weigh 46kg?

you should be looking at horses between 14hh and 15hh, depending on the horses build, and what you want it to do. i would advise that you get one of your friends/family/instructor to look at you and the horse while mounted, and assess whether you look to big/small on their back. other than that as a rough guide a horse can carry about 1/4 of is weight, this can easily be found with a weight band around the belly of the horse. i think as long as you do not look or feel actively to big/small on the horse than you should be alright. always remember safety first when riding/handling your horse and if they are to strong for you get someone more experienced in to help you.