Without seeing an example of your issue, the only advice I can think to give is:

•Use your bow to pull carefully. Wait until wanderers leave, pick small groups, target stragglers, etc.
•Make sure you’re in Blood Rage stance and not Reaver stance. This is where all your self-healing comes from.
•Don’t worry about buying expensive healing potions; the regular ones for your level are fine. Make sure to drink one early if you think the pull will be rough.
•Invest in the Insanity/Blood Fury feats. This lets your Blood Rage stack higher, and lets you spend stacks as necessary. IIRC, you won’t get any self-heal procs if you’re maxed on stacks, so having a way to lower your stack is helpful.
•Use CC abilities often, especially against larger pulls.