The problem is that you’re looking at what Tertullian wrote with a modern mind set and even the Protestant Scholar JND Kelly disagrees with you because of this...
“YET WE SHOULD BE CAUTIOUS ABOUT INTERPRETING SUCH EXPRESSIONS IN A MODERN FASHION. According to ancient modes of thought a mysterious relationship existed between the thing symbolized and its symbol, figure or type; the symbol in some sense WAS the thing symbolized. Again, the verb -repraesentare-, in Tertullian’s vocabulary [Cf. ibid 4,22; de monog. 10], retained its original significance of ‘to make PRESENT.’
“All that his language really suggests is that, while accepting the EQUATION of the elements with the body and blood, he remains conscious of the sacramental distinction between them [as do Catholics today — see the Catechism, paragraphs 1333ff].
“In fact, he is trying, with the aid of the concept of -figura-, to rationalize to himself the apparent contradiction between (a) the dogma that the elements are NOW Christ’s body and blood, and (b) the empirical fact that for sensation they remain bread and wine.” (JND Kelly, EARLY CHRISTIAN DOCTRINES, page 212)
From http://www.philvaz.com/apologetics/num29.htm
“JND Kelly disagrees with you”
JND Kelly doesn’t disagree with me, since you’re quoting him speaking on the Real Presence, not transubstantiation. That is, that despite their belief in the distinction between the symbol and the reality, that the reality was, in some way, present in the symbol. In his chapter on the development of doctrine on the Eucharist:
“Eucharistic teaching, it should be understood at the outset, was in general unquestioningly realistic... Among theologians, however, this identity [realism] was interpreted in our period in at least two different ways, and these interpretations, mutually exclusive though they were in strict logic, were often allowed to overlap. In the first place, the figurative or symbolic view, which stressed the distinction between the visible elements and reality they represented, still claimed a measure of support. It harked back, as we have seen, to Tertullian and Cyrpian... Secondly, however, a new and increasingly potent tendency becomes observable to explain the identity as being the result of an actual change or conversion in the bread and wine.”(JND Kelly, Early Christian Doctrine pg 440)
Kelly asserts that an actual change in the elements, IOW, such as transubstantiation, is the later view, whereas the earlier view is the symbolic view, or the consubstantiation view. Keep in mind, what you’re looking for is evidence of transubstantiation. That is, that the symbols aren’t symbols at all, but actually become the real physical body of Jesus Christ. Consubstantiation or a spiritual presence within the Eucharist does not aid you. Kelly is an Anglo-Catholic, so I do disagree with him a great deal, but he does not support Roman theology.