I don't think it is an issue with you not being "yourself". It's more like you have not shown (all) of yourself. Each of us has different facets of our personality that we keep to ourselves. We do this at work and with people we don't know well, or uncomfortable with. However it is unusual to be (in love) with someone and hold back (unless) one has lied or misled them from the beginning of the relationship. Pretending to like things you really don't, covering up facts in your history, or just not saying what is on your mind when asked.
You might need to examine the person you are (today). Human beings do change and evolve overtime. Sometimes growing is "uncomfortable" because it's not what we have known in the past. Unless you HATE where you are or what you are doing there is no need to take yourself back to who you were 1 1/2 years ago. Sometimes we have to make (changes) in order to accomplish our goals. Remember any change you have made was (your choice). Your significant other did not ask you to change.
When I hear you say, "you haven't been honest with yourself or your significant other." It sounds like you are NOT happy with the way things are. It's possible you may be just looking for a way to end the relationship or "shake up" things. This is where you have to be (honest) with yourself. When people change and it leads to positive results they usually don't want to go backwards. You only want to go back when you aren't happy with where you are today.