Hi , I'm so sorry you're dealing with all this.
Before addressing your question, I just wanted to note that blood in the stool isn't normally a symptom of IBS (I'm not sure about gastritis) - did your doctor perform any tests to rule out other conditions? This article talks about the importance of not ignoring such symptoms: https://irritablebowelsyndrome.net/living/new-symptoms.
You're not the only one experiencing gastritis and IBS at the same time, these advocates are, too:
https://irritablebowelsyndrome.net/living/gastritis , https://irritablebowelsyndrome.net/living/gastritis-disorder .
As for anemia, I'm going to share the following articles with you: https://irritablebowelsyndrome.net/living/iron-deficiency-anemia, https://irritablebowelsyndrome.net/living/anemia.
It could however also be a symptom of IBD: https://irritablebowelsyndrome.net/living/ibd.
From what I've read, anemia doesn't seem to be the cause of digestive issues but rather the other way around. I'm not an expert though.
I hope that this helps and that other community members will chime in as well!
Wishing you all the best,
Karina (team member)