Am i feeling like this because of low iron?

I missed my period about 3 months ago but then i got it early the following month but it was super short almost like it was just spotting. I just got a pretty "normal" period this month. i really thought i was going to take a pregnancy test and it say positive because i had all early symptoms but when I had taken 2 home pregnancy test about 2 months ago and they both came out neg. So i just thought i was wrong. I think i might have something else going on why im not feeling well. I cant sleep on my stomach really because it hurts it feels like theres alot of pressure on it. (and ive always slept on my stomach with no problems), Im always always tired. I dont even need to do much and i just want to sleep. sometimes i feel like i can eat and eat and sometimes the thought of food makes me feel like ewww. I know i have low iron becuase i went about a month & a half ago to donate blood and i couldnt because they said my iron was low. I bought some iron pills and have been taking them but i still havent seen an improvement. If anyone has had any thing like this and knows what it is caused by i would love to hear what you have to say. Thank you so much for your time..