Underweight TTC

Is anyone underweight TTC? I have always been very small for my age due to my high metabolism, and my doctor told me that since I eat normal there's nothing wrong with my weight. I'm 5'3 and 18 years old (I'm also married and financially stable enough to be TTC before anyone judges) and my weight constantly fluctuates between 85-95. I've been trying to conceive for nearly a year. Any advice/tips from someone who has been in my situation?