History and exam. Sounds like she's bleeding - do we have a diagnosis re: where the bleeding is from? Ie, previa vs uterine rupture vs GSW vs leeches from her holistic internet-trained midwife ... That degree of hypotension & tachycardia is a lot worse than what I'd expect from someone who isn't bleeding. Hb of 7 isn't too far out there for a pregnant sickler, chronic anemia alone doesn't explain those vitals, and acute blood loss won't be reliably reflected in that number anyway.
Other concerns -
1) As with all JWs, determine what products they will accept. If no RBCs, then what about FFP, platelets, cryo, albumin, 7A, etc. Some will surprise you with what they'll take. Cell saver? Maybe.
2) Sickler - do the usual things to reduce the risk of sickling (avoid hypoxia, hypothermia, etc) but you're probably somewhat screwed there as she's already vasoconstricted, peripherally cold, and likely in need of pressors.
LUD, oxygen. Phenylephrine followed by crystalloid resuscitation and better access. If by chance these maneuvers result in a normotensive mom and FHR >120, reassess. I'd have a heavy bias against regional even if she appears stable now. Otherwise GA - etomidate/succ RSI/delivery. Continued resuscitation / bleeding control.