Compilers are a specialized topic - and syntax design is fiddly - but it really is no harder than any other sort of program. A lot of the hard theoretical work was done back in the sixties and seventies. You don’t have to start from scratch. These days it’s “only” a matter of implementing the features you want and making sure your syntax doesn’t leave itself open to multiple interpretations. (just as arithmetic, e.g. ‘5 × 4 - 1’ requires some rules to make sure there’s only one correct interpretation, so do language syntaxes need to be unambiguous to parse. )
Don’t get me wrong - writing a language is a lot of work and it’s super cool that OP has done this! I just want to stress that language development is 100% doable with an undergrad degree. If you understand recursion and how to parse a string you already have all the theory you need to get started.