PPD 3 months in?

I recently had baby #2 back in December. While I love my girls with all my heart, I think I may have a mild case of PPD. I am having a lot of trouble coping with my new role as a mom of 2...I am sleep deprived for sure, which I know is probably exacerbating my feelings, but I just feel so listless and exhausted most days. I realized I don't really have the energy to play with my older DD and it makes me feel like a horrible mother. Sometimes I just want to leave and not tell anyone, just so I can get some rest and time to myself. On my deepest, darkest days, I wish I didn't have to deal with the responsibility anymore because I don't feel as though I'm cut out for it.

I do have some anxiety issues which I see a therapist for weekly, but I haven't specifically mentioned to her my thoughts that I may have PPD even though she knows I am struggling to adjust to my new life. I guess I'm scared to actually admit it out loud because I feel like I'd be admitting the "truth" -- that I'm a failure and not cut out to be a mom. Also, I am breast feeding and I'm worried that if I had to take medication, it would be harmful to my baby (rationally I know that there are meds that are safe to use while BFing).

LO is so young and won't remember, but my older DD is 3 and I feel like she knows that Mommy isn't acting like herself and I am scared my relationship with her will suffer if I dot get a handle on this somehow. I know I need to talk to someone (I know my therapist would be a good start) and tell them exactly what I've said here, but it's just so hard to make that first step for some reason. Even putting it out here was tough, but I do feel a little bit better laying it out. Thanks for reading and if anyone has insight/advice it will be much welcomed.