Hi. Welcome. The poor man’s tilt table test ou can do at home is to take your pulse while sitting at rest. Then stand and take your pulse again. Continue standing and taking your pulse. If your pulse increases by over 30 beats per minute that is considered positive for POTS. The easiest and most accurate way to do this is with a pulse ox because it gives an instant read out of your pulse. They are about $50 here in the pharmacy/drug store.
Hope this helps. Let us know how the “at home” version goes.