Oh gosh Happeechic, you need better care than this.
So if you haven't had a period for 6 months (including on HRT) then you definitely need more estrogen! You are not making enough estrogen yourself to cause the lining of your uterus to build up each month, if you are not bleeding. And if you are only on 1.5 pumps, that is a miniscule dose. The normal *starting* dose is 2 pumps. And even that is too low for the vast majority of women.
The official guidelines from the NHS is that you need to increase first to the maximum licensed dose (4 pumps) if you still have symptoms. If you get to 4 pumps and still have symptoms, then they will (or should) offer you a blood test to check if you are absorbing it okay and what your levels are. Your GP may tell you to also increase your progesterone.
Just for reference point, I am on 6 pumps of gel a day PLUS 300mcg of patches. (3x 100mcg.) Each 100mcg is the equivalent of 4 pumps of gel. So I am on 4.5x the max licensed dose. This gets my serum level to around 850pmol, which is where I need it in order not to have neurological symptoms at night. (The palpitations stopped when I got to around 300, so you may not need as high as me, but I don't want you to be afraid of estrogen.)
If you want to do your own test, at home, you can any time - for about £50. Look up the Randox Health Tasso test. It has to be the Tasso option and not the finger prick because it attaches to your arm so it means you don't get contaminated results (if you use your fingers for a home finger prick test and you have gel, you can get falsely high results). This is assuming you don't apply the gel to your shoulders of course, but only your legs.
If I were you (and if your GP will allow and prescribe more gel) I would gradually increase up to the max licensed dose of 4 pumps without bothering about testing. You might find it a smoother ride to split it with 2 pumps in the morning and 2 at night, for eg.... so you get more regular levels.