Things to consider will you need a lot of custom database management? Are you comfortable deploying MySQL or another DB from command line? Are there tools in AWS that you will benefit from using - will they save you time compared to building them yourself, e.g. SQS versus managing a queue system.
If you are prepared to manage these are yourself, feel comfortable doing so, and your tech stack won't benefit from the AWS tools too much, using a VPS might be the way to go.
That said you're going for MVP - and you have 6 months to do it. Get going, move fast and break things!