New mattress too soft or too firm - lower back tension

Hey everyone looking for recommendations here. Just bought a new mattress from Ikea model Anneland in medium firm (probably a mistake I know). Now it’s been a couple of nights trying it out and I’m waking up with lower back and hip tension. I’m a side sleeper lightweight 130lb female.

I have trouble figuring out if it’s because the new mattress is too firm or too soft. It does curve a descent amount under the body because the springs under it are really soft. However it doesn’t have much plush on top of it (even though it’s supposed to be memory foam upper layer) Last time I had this type of pain I was sleeping on a pure latex bed that was a tad top firm and also didn’t have enough cushioning on top for the body not to roll over. Plus the weird thing it that the older mattress we replaced was much firmer spring coils but it didn’t give me lower back pain.

I’m worried the mattress might just not be supportive enough (meaning it sinks too much) and there’s nothing to do but to return it, OR on the contrary if it lacks cushioning on top and could be fixed with a thin topper?