I have coolant in my oil and oil in my coolant reservoir

Unfortunately this is most like the head gasket. Just because it is not overheating doesn't discount the head gasket. We need to do a compression check and then if there are low cylinders, you need to do a cylinder leakage to confirm the head gasket but I think we can safely assume that after you find low compression.

Let me know if you have questions. Thanks

https://www.2carpros.com/articles/coolantantifreeze-in-the-engine-oil

https://www.2carpros.com/articles/how-to-test-engine-compression

If there is no overheating and oil and coolant are mixing I would suspect a faulty oil cooler. The cooler is next to the oil filter. You would need to replace the cooler, change out oil, replace the radiator and heater hoses with expansion tank and flush out the rest of the cooling system.

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars