Can I mix batches of breastmilk?

Abbie
This may be a really dumb question but j was wandering if I were to pump a little bit In the morning and then a little bit at night can I mix the two batches together in a bottle to feed my LO also how do I hear breastmilk and know it's the right temperature? Iv been bfe for the past 11 days but due to continuous latching issues I need to pump some but have no idea what I'm doing!