Engine oil level is decreasing, but no evidence of a leak

Engine oil level is decreasing, but no evidence of a leak. Was substantial and now seems to not be too much of a problem. Maybe a quart every other month. Is this something I should be really concerned about?

No lights have come on, but a few months ago my car was several quarts low. I have made a habit of checking it since then, but it doesn't seem to be that severe anymore. Maybe needing a quart every other month or so. It does get regular oil changes.

I believe it is also leaking from the transmission oil cooler line. It is not burning oil, there is not smoke or oil puddles under my car, just a water like substance that leaked a few times, but hasn't been leaking as of late. I don't know if it is a problem since it seems to be subsiding, but wanted to know if it is major or not before trying to tackle the issue.