The standards for the breed are of a horse (Icelandic language has no word for pony) between 13/14 hands, and 730 to 840 lbs.
At 155, you are not counting a saddle/pad either. Which could put it up to 180 or so?
Which could be fairly close to 1/3 of weight of horse in other words. To me? That is too much.
Another consideration, if you carry much weight in thighs/hips/rear end, is your saddle fitting you and not also being too long for the back of the horse.
Baby Huey is shortbacked, and that does present a problem as the saddle I really need to fit my rear is going to be too long for his back.
Also, if you can only have one horse, due to land/budget, I would be thinking ahead to wanting to ride more and in various settings too, and if the size would be troublesome then.
And I know that many people see no trouble with weight of rider being a problem for a horse, but I do. Whether it is a big barreled cowboy on a small horse, or an obese woman on one, is the same to me. Just because you can, does not mean you should.
I'd look at other breeds too I think, if it were me.
Horses make me a better person.