Step mom struggles

Bree

Anyone else here a step mom? I'm struggling a bit this week and I feel horrible but I need to vent. So, I've been in my step daughters life since she was a baby. She's now 4. Her bio mom is very up and down. We have 50/50 custody with a week on week off arrangement (verbal only, no court order). Bio mom abandoned her daughter for almost the first year of her life, having very little contact and my fiance did almost all of the parenting. When I came into the picture bio mom decided she didn't like another woman parenting her child and came back into the picture and demanded her 50/50, which she got. For my first 6 months living with my fiance and step daughter it was never 50/50, bio mom called us almost every day during her week getting us to take my step daughter and always gave a bs reason. So it was more like 90/10. Finally when my step daughter turned 3 bio mom stuck to the 50/50 but now bio mom has a 6 month old son and seems to be reverting back to her old ways. She "hurt her back" this week (her week with my step daughter) and sent her to me and my fiance exactly 2 days into her week. She only just took my step daughter back yesterday and is now dropping her off tonight (our regular drop off time) and refuses the extra time we offered her to make up for her lost time. I am beyond frustrated. I love my step daughter dearly, shes my baby. However, I am 25 weeks pregnant and exhausted as I do most of the work with her (bathing her, making her snacks/meals, doing her hair etc..) so I really do enjoy our days off from her so I can have some down time with my fiance seeing as how in 15 weeks we will have our son and no longer get that alone time. So I lost almost my entire week of downtime and will now have another full week of being a very hands on step mom and will constantly have to answer my step daughters questions about why she didn't get to see her mom very much. It breaks my heart and takes so much out of me. I feel bad, but I was hoping bio mom was going to take us up on our offer of letting her keep my step daughter until Sunday so I could have the weekend to relax. I just dont understand how a mom can just not care. She was completely able and willing to take care of her 6 month old son with a hurt back but not her 4 year old daughter? She has a fiance to help her, her mom to help her and my MIL even offered to take my step daughter to and from school for bio mom just so she wouldn't have to leave the house and she still refused and would rather send her off to me and my fiance. She didn't even try to call her or anything. My fiance and I love the extra time and everything but it is still so exhausting and I just feel bad for being a bit upset that I dont get more of a break.