You could try something like an auto injector. These aren't like the epipens. They're a device that fits around a regular syringe.
Also, if it helps, I'm guessing you're referring to estradiol valerate or estradiol enanthate. Either of those can be safely delivered as a subcutaneous injection rather than an intramuscular one. This allows you to use a much shorter and thinner needle. I inject EEn with little guys like these.