Treat yourself as you would treat anyone else in your database.
Just realize that different databases allow/require you to handle persons in subtly different ways.
At a purely research process level, you need to record two items of evidence (your Mom's statement and your birth certificate). At the conclusion level you need to add a conclusion level person object for yourself that refers, however your system allows you to do it, to the two items of evidence.
In some systems this just means that you create a person record for yourself and then add the facts from the two sources, having those facts contain references to the sources. So you will have to provide source records in the formats allowed by your system.
In other systems you can add separate person-like records for each fact, and then have your conclusion person refer to them. In such a system you would have 1) your Mom's statement as a source; 2) your birth certificate as a source; 3) the facts about you from your Mom's statement as an evidence level record; 4) the facts about you from your birth certificate as another evidence level record (presumably you would also have evidence level records about your Mom and Dad taken from the same birth certificate); and 5) the "conclusion" person record, with references to the evidence-level records or facts, about yourself representing your "beliefs" about your own existence.
Is this enough to establish "proof"? Yes.
Do you need to add a separate note stating you have made the conclusion? No. The fact that you have a "conclusion" level person in your database that refers, however you are able to do it, to items of evidence, is a sufficient statement of conclusion.