You should be able to if your therapist or PCP will give you a diagnosis of gender dysphoria. I’m not sure about Planned Parenthood, or other clinic-type places, but my insurance needs an endocrinologist to prescribe the hormones. I’m not definitely planning any surgeries, but it didn’t stop getting spironoclactone and estradiol after some baseline bloodwork.
I’m speaking from a personal viewpoint as a transwoman here: the purpose of the hormones isn’t to transform us into “women”, but more to help us with the gender dysphoria by making some subtle changes to our bodies (except for boobs – nothing subtle there!) and balancing our genetic and hormonal imbalance we’ve had all along.
The requirement to live in your true gender for at least a year is generally for bottom surgery (vaginaplasty), so that you are settled in with your mindset and social patterns before taking such an irreversible step. Breast augmentation can be done sooner, but most medical experts recommend waiting for a couple of years to see how the estradiol will impact our busts. I won’t wait that long to socially transition (go femme full-time). I’m planning to do that in January next year, which will be only 9 months in on estradiol. But I will wait to see how my breasts develop for maybe 18 months before considering BA. I started so late in life I may not get much breast growth at all, but so far in 3 months I have pretty decent breast buds started and the tissue is definitely developing!
So, do be aware that HRT will affect your breasts to some extent. I’m sure your endo can tailor a dosage to your needs, but a low dose may not help the dysphoria much, either.