Based on your weekly miles you could probably ride a century now, but you might not enjoy the last hour or two. Bike fit, hydration, fueling, and pacing are the critical elements. 100 miles isn't so long everything must be perfect, but the better you are at each of these, the more likely to have an enjoyable ride.
Try to get these sorted out so you can finish a 50 fully hydrated, fully fueled, and having no discomfort other than tired muscles. Keep eating and drinking all the way to the finish.
Good luck.